Microbee Premium Series Models
The Microbee Premium Series became available early in 1986 and was showcased at the PC86 show in Sydney in March. Three models comprised the initial Premium release:
- PC85 Premium
- 64K Computer in a Book Premium (CIAB Premium)
- 128K Small Business Computer Premium (SBC Premium)
Standard versions of the same machines were still available following the Premium release and retailed for around $100 less than their Premium counterparts. While the Standard and Premium variants of the same machine look very similar externally, internally the Premium machines use a completely redesigned Main board that provides significant technical improvements over the earlier Standard board and a number of new features, including:
- Colour video output (CGA compatible)
- Videotex/Viatel compatible 40 column display
- Glitchless display, eliminating interference seen on Standard models during CPU access to video RAM
- Expanded PCG RAM, removing the HIRES character count limitations that apply to Standard models
- 4 new keyboard arrow keys
- Speaker volume control
- Provision for an on-board real time clock (not fitted as standard)
- Provision for an on-board sound chip (not fitted as standard)
- Provision for a 50 way expansion interface on the Main board (not fitted as standard)
- Provision to generate negative output voltages on the Serial port (not fitted as standard)
The 64K CIAB model with its distinctive external "book" disk unit was discontinued in both Standard and Premium versions very soon after the initial Premium release as falling RAM prices made the 128K SBC a more attractive proposition for no additional cost. At around the same time, a new "Modular Microbee" series was announced that allowed customers to mix and match machines, floppy drive units and peripherals as they liked. The modular SBC style external disk unit could now accommodate either 5.25" or 3.5" floppy drives as well as a hard drive.
The final addition to the original Premium range was announced in the Summer 1988 edition of Online magazine as the 128K Overdrive. This machine is technically very similar to the 128K SBC Premium, but removes the need for an external disk unit entirely by mounting one or two 3.5" floppy drives directly on top of the traditional Microbee case, giving a similar side-facing drive configuration as the 256TC.
PC85 Premium
Overview
Name
|
Category
|
Release Date
|
Description
|
Microbee PC85 Premium
|
Premium
ROM based
|
Early 1986 (March?)
|
The PC85 Premium is the entry level model of the Premium Series. It is ROM based and is fitted with 32KB of battery backed static RAM.
This machine uses the same PAK ROM Core board as the Standard PC85B (ie, types MB8328-4 & MB8328-6), with some minor factory modifications applied to allow the Basic A ROM to be upgraded from 8KB to 16KB. This modification, combined with the standard 8KB Basic B ROM, provides a total of 24KB Basic ROM capacity required to accommodate the new Premium version of Microworld Basic (version 5.29e). A bank switching technique is used to page the two halves of the 16KB Basic A ROM into the standard 8KB Basic A ROM memory map.
The same bundled software packages as the Standard PC85B are also supplied with the new Premium model, including:
- PC85 System Menu/Command Menu
- Microworld Basic
- WordBee
- Telcom
- Calculator
- Monitor
- Self Test
- Database
- Spreadsheet (Busy-Calc)
- Graphics
- Videotex/Viatel
PC85 Premium Microbees will likely have a rectangular label fixed to the right side of the keyboard fascia stating "PC85", together with a second gold coloured "Premium Series" fascia label.
|
Details
PC85 Standard vs Premium Brochure
PC85 Standard vs Premium Brochure
|
CPU
|
Zilog Z80 @ 3.375MHz
|
RAM
|
32KB total capacity. A rechargable backup battery is fitted as standard to make the RAM non-volatile.
Uses CMOS Static RAM (SRAM), eg Hitachi HM6116 (each 2KB)
|
ROM
|
Up to 128KB total capacity, using a combination of 8KB Mask ROMs (or 2764 EPROMs) and 27128 EPROMs.
See the Overview section above for details of specific ROM packages that are included with this machine.
|
Storage
|
Cassette tape via an external recorder with a load/save speed of 300 or 1200 baud.
|
Video
|
Colour video output is provided as standard via a DB9 socket at the rear. Output is CGA compatible and provides a total of 16 foreground and 16 background colours, including half intensity. The Premium colour palette differs from that provided by the colour add-on boards that can be fitted to Standard models.
Standard monochrome composite video output is also provided via the 5 pin DIN socket at the rear.
Three main display resolutions are available:
- 64*16 characters.
- 80*24 characters.
- 40*24 characters (for Videotex/Viatel).
Uses Synertek 6545 CRT controller.
|
Graphics
|
Two graphics modes are available using a Programmable Character Generator SRAM (PCG):
- Low resolution (LORES):
- 128*48 pixels on a 64*16 character display.
- High resolution (HIRES):
- 512*256 pixels on a 64*16 character display.
- 640*264 pixels on a 80*24 character display.
PCG RAM capacity is 16KB as standard, but can be expanded to 32KB. The standard 16KB configuration provides a maximum of 1024 unique graphics characters which is sufficient to allow unrestricted HIRES graphics on a 64*16 character display. The expanded 32KB configuration provides for 2048 unique graphics characters so allows unrestricted HIRES graphics on a 80*24 (or 80*25) character display.
|
Fonts
|
Dual fonts to support 64*16 and 80*24 character displays. Both fonts support upper and lower case characters (128 characters in total per font).
Uses a single 4KB ROM.
|
Sound
|
Internal speaker. Generates sound through software bit bashing.
An optional SN76489AN sound chip can also be installed on the Main board.
|
Keyboard
|
64 key QWERTY style with a bit-paired layout. This includes 4 arrow keys on the bottom row that are not provided on Standard models.
|
Serial port
|
An RS232-like serial port using a DB25 socket at the rear. The port is configured as Data Terminal Equipment (DTE) but does not implement all RS232 standard signals and the default factory configuration does not provide negative voltages on output. Nevertheless, it is compatible with many standard RS232 peripherals.
Additional components can be fitted to the Premium Main board that will enable negative output voltages on this port, if required.
Microworld Basic uses this port to provide 300 and 1200 baud serial communications through software bit bashing.
|
Parallel port
|
8 bit parallel I/O port via a DB15 socket at the rear.
|
Expansion interface
|
An interface to the Z80 bus is available at the rear, but the associated 50 way connector is not fitted as standard. This was available as an option.
The PC85 Premium and TeleTerm (uniquely) have provision for two 50 way expansion interfaces - one on the Premium Main board and one on the Core board.
|
DIN port
|
A 5 pin multifunction DIN socket at the rear carries:
- Power input.
- Composite video output for connection to a video monitor.
- Tape recorder output for connection to an external recorder's AUX IN/MIC socket.
- Tape recorder input for connection to an external recorder's EAR (earphone) socket.
|
System Clock
|
The master clock runs at 13.5MHz. This provides a 13.5MHz video dot clock and is divided by 4 to provide the 3.375MHz CPU clock.
|
Real Time Clock
|
Software based interrupt driven clock provided by the Telcom v3 ROM (if fitted).
An optional hardware based RTC can also be installed on the Main board.
|
Case
|
Premium
|
Power
|
12V 1A plugpack
|
|
Included Software
|
Version
|
Microworld Basic in ROM
|
5.29e
|
WordBee in ROM
|
1.3 Rel 03
|
Telcom in ROM
|
3.21 Premium
|
Calculator in ROM
|
|
Monitor in ROM
|
|
Database in ROM
|
|
Spreadsheet (Busy-Calc) in ROM
|
III
|
Graphics in ROM
|
|
Videotex in ROM
|
2.35
|
|
Included Documentation
|
- Premium PC85 User's Manual
- Microbee Basic with Advanced Programmming & Reference Manual
- Videotex Manual
|
|
Pricing
|
$
|
Microbee PC85 Premium
|
$599.00
|
Microbee PC85 Premium with monochrome monitor
|
$699.00
|
Microbee PC85 Premium with monochrome monitor and 1200/300 baud BeeModem
|
$849.00
|
|
Notes
- While the PC85 Premium appears to have been sold in only one RAM configuration (32K), some testing has been performed to determine exactly how much RAM is required by each of the integrated software components. Results are:
- PC85 Premium
- PC85 System Menu/Command Menu: Requires 3K minimum.
- Microworld Basic (5.29e): Requires 3K minimum.
- WordBee (1.3 Rel 03): Requires 3K minimum.
- Telcom (3.21): Requires 3K minimum.
- Calculator: Requires 3K minimum.
- Database: Requires 32K, any less and it flashes a blank screen then exits back to the shell.
- Spreadsheet (Busy-Calc III): Requires 32K to be present or the program coded in MWB reports an array DIMension error at line 18.
- Graphics: Requires 16K minimum.
- Videotex (2.35): Requires 8K minimum.
64K Computer in a Book Premium (CIAB Premium)
Overview
Name
|
Category
|
Release Date
|
Description
|
Microbee 64K Computer in a Book Premium (CIAB Premium)
|
Premium
Disk based
|
Early 1986 (March?)
|
The 64K CIAB Premium is the entry level disk based model of the Premium Series. It uses the same DRAM Core board as the Standard CIAB.
This model unfortunately had a very short life of only a few months as the CIAB in both Standard and Premium configurations was announced as discontinued in May 1986. Falling DRAM prices meant that the 128K SBC could now be sold at the old 64K CIAB price, so the smaller model was no longer an attractive option. As part of the new "Modular Microbee" that was announced at around the same time, customers who preferred the CIAB's 3.5" floppy disk format were now able to choose an SBC style external disk unit with this type of drive fitted instead of the previous 5.25" only offering.
This machine is rarely seen today as a consequence of it's short life. If you're lucky enough to spot one you will probably see a black & white "64K RAM" label on the right side of the keyboard fascia, together with a second gold coloured "Premium Series" fascia label.
|
Details
CIAB Standard vs Premium Brochure
Modular Microbee Brochure
Modular Microbee Brochure
CIAB Standard vs Premium Brochure
|
CPU
|
Zilog Z80 @ 3.375MHz
|
RAM
|
64KB total capacity.
Uses Dynamic RAM (DRAM) with 8x 4164 RAM ICs
|
ROM
|
8KB Boot/Monitor ROM (a single 2764 EPROM)
|
Storage
|
Either:
- Single or dual half height 3.5" SSDD 80 track floppy disk (386K formatted capacity) via separate external disk units, or
Cassette tape via an external recorder with a load/save speed of 300 or 1200 baud.
|
Video
|
Colour video output is provided as standard via a DB9 socket at the rear. Output is CGA compatible and provides a total of 16 foreground and 16 background colours, including half intensity. The Premium colour palette differs from that provided by the colour add-on boards that can be fitted to Standard models.
Standard monochrome composite video output is also provided via the 5 pin DIN socket at the rear.
Three main display resolutions are available:
- 64*16 characters.
- 80*24 characters.
- 40*24 characters (for Videotex/Viatel).
Uses Synertek 6545 CRT controller.
|
Graphics
|
Two graphics modes are available using a Programmable Character Generator SRAM (PCG):
- Low resolution (LORES):
- 128*48 pixels on a 64*16 character display.
- High resolution (HIRES):
- 512*256 pixels on a 64*16 character display.
- 640*264 pixels on a 80*24 character display.
PCG RAM capacity is 16KB as standard, but can be expanded to 32KB. The standard 16KB configuration provides a maximum of 1024 unique graphics characters which is sufficient to allow unrestricted HIRES graphics on a 64*16 character display. The expanded 32KB configuration provides for 2048 unique graphics characters so allows unrestricted HIRES graphics on a 80*24 (or 80*25) character display.
|
Fonts
|
Dual fonts to support 64*16 and 80*24 character displays. Both fonts support upper and lower case characters (128 characters in total per font).
Uses a single 4KB ROM.
|
Sound
|
Internal speaker. Generates sound through software bit bashing.
An optional SN76489AN sound chip can also be installed on the Main board.
|
Keyboard
|
64 key QWERTY style with a bit-paired layout. This includes 4 arrow keys on the bottom row that are not provided on Standard models.
|
Serial port
|
An RS232-like serial port using a DB25 socket at the rear. The port is configured as Data Terminal Equipment (DTE) but does not implement all RS232 standard signals and the default factory configuration does not provide negative voltages on output. Nevertheless, it is compatible with many standard RS232 peripherals.
Additional components can be fitted to the Main board that will enable negative output voltages on this port, if required.
Microworld Basic uses this port to provide 300 and 1200 baud serial communications through software bit bashing.
|
Parallel port
|
8 bit parallel I/O port via a DB15 socket at the rear.
|
Floppy interface
|
The DRAM Core board provides a Shugart standard 34 way floppy disk interface at the rear for connecting the external disk unit.
|
Expansion interface
|
An interface to the Z80 bus is available at the rear of the Main board, but the associated 50 way connector is not fitted as standard. This was available as an option.
|
DIN port
|
A 5 pin multifunction DIN socket at the rear carries:
- Power input.
- Composite video output for connection to a video monitor.
- Tape recorder output for connection to an external recorder's AUX IN/MIC socket.
- Tape recorder input for connection to an external recorder's EAR (earphone) socket.
|
System Clock
|
The master clock runs at 13.5MHz. This provides a 13.5MHz video dot clock and is divided by 4 to provide the 3.375MHz CPU clock.
|
Real Time Clock
|
Software based interrupt driven clock provided by the Telcom v3 ROM (if fitted).
An optional hardware based RTC can also be installed on the Main board.
|
Case
|
Premium
|
Power
|
Power is supplied from the external disk unit via a separate cable integrated into the DIN plug.
|
|
Included Software
|
Version
|
Boot/Monitor in ROM
|
bn55
|
|
Included Documentation
|
- Microbee Computer-In-A-Book Manual
|
|
Pricing
|
$
|
Microbee 64K CIAB Premium, single 3.5" disk drive
|
$1095.00
|
Microbee 64K CIAB Premium, single 3.5" disk drive with monochrome monitor and 1200/300 BeeModem
|
$1245.00
|
Add-on 3.5" disk drive (2nd drive/volume)
|
$345.00
|
|
Notes
- A bank switching technique (port 50) is used to switch components of RAM and ROM into and out of view within the Z80 memory map. The full 64KB RAM and 8KB ROM capacity is available for use via this method.
128K Small Business Computer Premium (SBC Premium)
Overview
Name
|
Category
|
Release Date
|
Description
|
Microbee 128K Small Business Computer Premium (SBC Premium)
|
Premium
Disk based
|
Early 1986 (March?)
|
The 128K SBC Premium is the top-of-the-line disk based model of the initial Premium Series release. It uses the same DRAM Core board as the Standard SBC.
Customers were able to populate the SBC's external disk unit with a variety of drives as part of the new "Modular Microbee" system. Drive types that were available for use during the SBC's life are:
- 5.25" floppy drive - DSDD 40 track, giving 386KB formatted capacity (DS40 format)
- 3.5" floppy drive - SSDD 80 track, giving 386KB formatted capacity (SS80 format)
- 3.5" floppy drive - DSDD 80 track, giving 776KB formatted capacity (DS80 format)
- 10MB hard drive
- 20MB hard drive
The 128K SBC Premium is usually identified by a black & white "128K RAM" label on the right side of the keyboard fascia, together with a second gold coloured "Premium Series" fascia label.
|
Details
SBC Standard vs Premium Brochure
SBC Standard vs Premium Brochure
Microbee Shell (Early 2 version)
|
CPU
|
Zilog Z80 @ 3.375MHz
|
RAM
|
128KB total capacity.
Uses Dynamic RAM (DRAM) with 16x 4164 RAM ICs
|
ROM
|
8KB Boot/Monitor ROM (a single 2764 EPROM)
|
Storage
|
Either:
- Single or dual floppy drives, or single floppy drive + single hard drive. See Overview section above for specific drive types that were available, or
Cassette tape via an external recorder with a load/save speed of 300 or 1200 baud.
|
Video
|
Colour video output is provided as standard via a DB9 socket at the rear. Output is CGA compatible and provides a total of 16 foreground and 16 background colours, including half intensity. The Premium colour palette differs from that provided by the colour add-on boards that can be fitted to Standard models.
Standard monochrome composite video output is also provided via the 5 pin DIN socket at the rear.
Three main display resolutions are available:
- 64*16 characters.
- 80*24 characters.
- 40*24 characters (for Videotex/Viatel).
Uses Synertek 6545 CRT controller.
|
Graphics
|
Two graphics modes are available using a Programmable Character Generator SRAM (PCG):
- Low resolution (LORES):
- 128*48 pixels on a 64*16 character display.
- High resolution (HIRES):
- 512*256 pixels on a 64*16 character display.
- 640*264 pixels on a 80*24 character display.
PCG RAM capacity is 16KB as standard, but can be expanded to 32KB. The standard 16KB configuration provides a maximum of 1024 unique graphics characters which is sufficient to allow unrestricted HIRES graphics on a 64*16 character display. The expanded 32KB configuration provides for 2048 unique graphics characters so allows unrestricted HIRES graphics on a 80*24 (or 80*25) character display.
|
Fonts
|
Dual fonts to support 64*16 and 80*24 character displays. Both fonts support upper and lower case characters (128 characters in total per font).
Uses a single 4KB ROM.
|
Sound
|
Internal speaker. Generates sound through software bit bashing.
An optional SN76489AN sound chip can also be installed on the Main board.
|
Keyboard
|
64 key QWERTY style with a bit-paired layout. This includes 4 arrow keys on the bottom row that are not provided on Standard models.
|
Serial port
|
An RS232-like serial port using a DB25 socket at the rear. The port is configured as Data Terminal Equipment (DTE) but does not implement all RS232 standard signals and the default factory configuration does not provide negative voltages on output. Nevertheless, it is compatible with many standard RS232 peripherals.
Additional components can be fitted to the Main board that will enable negative output voltages on this port, if required.
Microworld Basic uses this port to provide 300 and 1200 baud serial communications through software bit bashing.
|
Parallel port
|
8 bit parallel I/O port via a DB15 socket at the rear.
|
Floppy interface
|
The DRAM Core board provides a Shugart standard 34 way floppy disk interface at the rear for connecting the external disk unit.
|
Expansion interface
|
An interface to the Z80 bus is available at the rear of the Main board, but the associated 50 way connector is not fitted as standard. This was available as an option.
|
DIN port
|
A 5 pin multifunction DIN socket at the rear carries:
- Power input.
- Composite video output for connection to a video monitor.
- Tape recorder output for connection to an external recorder's AUX IN/MIC socket.
- Tape recorder input for connection to an external recorder's EAR (earphone) socket.
|
System Clock
|
The master clock runs at 13.5MHz. This provides a 13.5MHz video dot clock and is divided by 4 to provide the 3.375MHz CPU clock.
|
Real Time Clock
|
Software based interrupt driven clock provided by the Telcom v3 ROM (if fitted).
An optional hardware based RTC can also be installed on the Main board.
|
Case
|
Premium
|
Power
|
Power is supplied from the external disk unit via a separate cable integrated into the DIN plug.
|
|
Included Software
|
Version
|
Boot/Monitor in ROM
|
bn56
|
|
Included Documentation
|
- 128K Premium User's Manual
- Microbee Basic with Advanced Programmming & Reference Manual
|
|
Pricing
|
$
|
Microbee 128K SBC with dual 5.25" floppy drives, hi-res monochrome monitor, software
|
$2095.00
|
Microbee 128K SBC with a single 10MB hard drive and a single 5.25" floppy drive, hi-res monochrome monitor
|
$3150.00
|
Microbee 128K SBC (computer only)
|
$499.00
|
External disk unit with a single 3.5" or 5.25" floppy drive
|
$450.00
|
External disk unit with dual 3.5" or 5.25" floppy drives
|
$650.00
|
|
Notes
- As with the CIAB, a bank switching technique (port 50) is used to switch components of RAM and ROM into and out of view within the Z80 memory map. The full 128KB RAM and 8KB ROM capacity is available for use via this method.
128K Overdrive
Overview
Name
|
Category
|
Release Date
|
Description
|
Microbee 128K Overdrive
|
Premium
Disk based
|
Late 1987 or early 1988
|
The 128K Overdrive was the final model to be released in the original Premium Series, almost 2 years after the initial series launch. It was designed to answer to a request from schools for a simple, compact and reliable machine that could be easily moved between classrooms. The machine is rarely seen today so presumably did not sell in large numbers.
Technically, the Overdrive is essentially the same as the 128K SBC Premium, except that a floppy drive enclosure has been added to the top of the machine to form a single self-contained unit and the SBC style external disk unit is no longer required. The disk enclosure could be configured with single or dual 3.5" DSDD 80 track floppy drives, each giving a formatted capacity of 776KB (DS80 format).
A new boot ROM was developed for the 128K Overdrive that displays a menu system at boot time if there is no bootable floppy disk inserted. Functionality is similar to that provided by the 256TC boot menu and includes a self test function and a machine code monitor.
|
Details
128K Boot ROM Menu (BN60)
|
CPU
|
Zilog Z80 @ 3.375MHz
|
RAM
|
128KB total capacity.
Uses Dynamic RAM (DRAM) with 16x 4164 RAM ICs
|
ROM
|
8KB Boot/Monitor ROM (a single 2764 EPROM)
|
Storage
|
Either:
- Single or dual 3.5" DSDD 80 track floppy drives, or
Cassette tape via an external recorder with a load/save speed of 300 or 1200 baud.
|
Video
|
Colour video output is provided as standard via a DB9 socket at the rear. Output is CGA compatible and provides a total of 16 foreground and 16 background colours, including half intensity. The Premium colour palette differs from that provided by the colour add-on boards that can be fitted to Standard models.
Standard monochrome composite video output is also provided via the 5 pin DIN socket at the rear.
Three main display resolutions are available:
- 64*16 characters.
- 80*24 characters.
- 40*24 characters (for Videotex/Viatel).
Uses Synertek 6545 CRT controller.
|
Graphics
|
Two graphics modes are available using a Programmable Character Generator SRAM (PCG):
- Low resolution (LORES):
- 128*48 pixels on a 64*16 character display.
- High resolution (HIRES):
- 512*256 pixels on a 64*16 character display.
- 640*264 pixels on a 80*24 character display.
PCG RAM capacity is 16KB as standard, but can be expanded to 32KB. The standard 16KB configuration provides a maximum of 1024 unique graphics characters which is sufficient to allow unrestricted HIRES graphics on a 64*16 character display. The expanded 32KB configuration provides for 2048 unique graphics characters so allows unrestricted HIRES graphics on a 80*24 (or 80*25) character display.
|
Fonts
|
Dual fonts to support 64*16 and 80*24 character displays. Both fonts support upper and lower case characters (128 characters in total per font).
Uses a single 4KB ROM.
|
Sound
|
Internal speaker. Generates sound through software bit bashing.
An optional SN76489AN sound chip can also be installed on the Main board.
|
Keyboard
|
64 key QWERTY style with a bit-paired layout. This includes 4 arrow keys on the bottom row that are not provided on Standard models.
|
Serial port
|
An RS232-like serial port using a DB25 socket at the rear. The port is configured as Data Terminal Equipment (DTE) but does not implement all RS232 standard signals and the default factory configuration does not provide negative voltages on output. Nevertheless, it is compatible with many standard RS232 peripherals.
Additional components can be fitted to the Main board that will enable negative output voltages on this port, if required.
Microworld Basic uses this port to provide 300 and 1200 baud serial communications through software bit bashing.
|
Parallel port
|
8 bit parallel I/O port via a DB15 socket at the rear.
|
Floppy interface
|
The DRAM Core board provides a Shugart standard 34 way floppy disk interface that is used for connecting the internal drives.
|
Expansion interface
|
An interface to the Z80 bus is available at the rear of the Main board, but the associated 50 way connector is not fitted as standard. This was available as an option.
|
DIN port
|
A 5 pin multifunction DIN socket at the rear carries:
- Power input.
- Composite video output for connection to a video monitor.
- Tape recorder output for connection to an external recorder's AUX IN/MIC socket.
- Tape recorder input for connection to an external recorder's EAR (earphone) socket.
|
System Clock
|
The master clock runs at 13.5MHz. This provides a 13.5MHz video dot clock and is divided by 4 to provide the 3.375MHz CPU clock.
|
Real Time Clock
|
Software based interrupt driven clock provided by the Telcom v3 ROM (if fitted).
An optional hardware based RTC can also be installed on the Main board.
|
Case
|
Premium
|
Power
|
10V 1.5A plugpack?
|
|
Included Software
|
Version
|
Boot/Monitor in ROM
|
bn57/58/59/60
|
|
|
Pricing
|
$
|
Microbee 128K Overdrive with single 3.5" floppy drive
|
$895.00 ($785.00 school price)
|
Microbee 128K Overdrive with dual 3.5" floppy drives
|
$1099.00 ($965.00 school price)
|
|
Notes
- A bank switching technique (port 50) is used to switch components of RAM and ROM into and out of view within the Z80 memory map. The full 128KB RAM and 8KB ROM capacity is available for use via this method.
