Difference between revisions of "Model A"

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[[Category:Hardware]]
 
[[Category:Hardware]]
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{| class="wikitable" style="float:right; margin-left: 10px;"
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| <div align="right">
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<img src="http://beebwiki.mdfs.net/images/4/47/BBCMicro.png" width="256">
 +
</div>
 +
|-
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| BBC Micro
 +
|}
 +
 +
The first BBC Micros were the Models A and B, released with much fanfare in
 +
early 1982. Powered by a 2Mhz 6502A processor and with 16K and 32K of memory
 +
respectively, at the time the capabilities of the Model B far exceeded what
 +
most other 8-bit microcomputers were capable of. Both models came supplied
 +
with a fully fledged Machine Operating System and BBC BASIC, the enhanced
 +
version of the BASIC language that included support for advanced programming
 +
structures and a built-in 6502 assembler.
 +
 
The BBC Model A was created as a lower-cost variant to encourage higher
 
The BBC Model A was created as a lower-cost variant to encourage higher
 
sales outside of the schools sector. It was launched at a price of GBP £235
 
sales outside of the schools sector. It was launched at a price of GBP £235
Line 5: Line 21:
 
Acorn found they couldn't make it at the lower price.
 
Acorn found they couldn't make it at the lower price.
  
 +
Early models were marked as 'BBC Microcomputer' on the Perspex keyboard
 +
strip - this, however, led to a trademark dispute with Brown Boveri
 +
Coporation, and the badges were changed to read 'British Broadcasting
 +
Corporation' instead.
 +
 +
All BBC Micros were capable of storing and loading data on tape via the
 +
cassette interface, but the Model B was also available fitted with an Econet
 +
interface (ANB02) additional 8271 floppy disc interface (ANB03) and with
 +
both disc and Econet interfaces (ANB04). Options on the Model A were by
 +
default limited to tape-only (ANA01) or Econet (ANA02).
 +
 +
The Model B's number of I/O and interfacing options was unmatched and some
 +
of the possibilities were near revolutionary for an 8-bit microcomputer of
 +
the day. Options comprised a cassette interface, RS-423 serial port,
 +
advanced analogue interface, floppy disc drive connector, parallel printer
 +
port, memory-mapped user port, 1MHz bus interface, the Tube connector for
 +
high-speed communication with a Second Processor, a choice of RF, composite
 +
and RGB video output, and the contemporarily significant option of an Econet
 +
network interface. The Model A lacked most of these options bar Econet due
 +
to being built without the necessary connectors and some of the required
 +
components.
 +
 +
The Model A was discontinued after the launch of the Acorn Electron.
 +
 +
== Variants ==
 +
Acorn released two versions of the Model A
 +
 +
* ANA01 - The standard Model A
 +
* ANA02 - Fitted with the optional [[Econet]] interface chips and socket
 +
 +
== Characteristics ==
 
While physically identical, the Model A lacked a number of internal
 
While physically identical, the Model A lacked a number of internal
 
components and interfaces.
 
components and interfaces.
  
−
16K RAM instead of 32K (although the empty sockets were present on the
+
'''Internal'''
−
motherboard). The Model A lacked a 6522 VIA chip (again with an empty socket
+
* 16K of RAM instead of 32K (The empty spaces were fitted with sockets to simplify upgrades)
−
on the board). None of the expansion ports on the underside of the machine
+
* 6522 VIA Chip
−
were fitted.
+
 
 +
'''Rear interface sockets'''
 +
* RGB port
 +
* Serial port
 +
* Analogue port
 +
 
 +
'''Underside interface sockets'''
 +
* Tube
 +
* User port
 +
* Centronics (printer) port
 +
* 1MHz Bus
 +
 
 +
[[File:ModelA Motherboard.jpg]]
 +
 
 +
All of these components could be installed to bring the machine up to full
 +
Model B specifications. Sockets were present on the board to allow easy
 +
installation of the missing chips, and it is quite difficult to find an
 +
unmodified Model A now.

Latest revision as of 13:31, 17 October 2020

BBC Micro

The first BBC Micros were the Models A and B, released with much fanfare in early 1982. Powered by a 2Mhz 6502A processor and with 16K and 32K of memory respectively, at the time the capabilities of the Model B far exceeded what most other 8-bit microcomputers were capable of. Both models came supplied with a fully fledged Machine Operating System and BBC BASIC, the enhanced version of the BASIC language that included support for advanced programming structures and a built-in 6502 assembler.

The BBC Model A was created as a lower-cost variant to encourage higher sales outside of the schools sector. It was launched at a price of GBP £235 (compared with GBP £335 for the Model B). This price rose to GBP £299 as Acorn found they couldn't make it at the lower price.

Early models were marked as 'BBC Microcomputer' on the Perspex keyboard strip - this, however, led to a trademark dispute with Brown Boveri Coporation, and the badges were changed to read 'British Broadcasting Corporation' instead.

All BBC Micros were capable of storing and loading data on tape via the cassette interface, but the Model B was also available fitted with an Econet interface (ANB02) additional 8271 floppy disc interface (ANB03) and with both disc and Econet interfaces (ANB04). Options on the Model A were by default limited to tape-only (ANA01) or Econet (ANA02).

The Model B's number of I/O and interfacing options was unmatched and some of the possibilities were near revolutionary for an 8-bit microcomputer of the day. Options comprised a cassette interface, RS-423 serial port, advanced analogue interface, floppy disc drive connector, parallel printer port, memory-mapped user port, 1MHz bus interface, the Tube connector for high-speed communication with a Second Processor, a choice of RF, composite and RGB video output, and the contemporarily significant option of an Econet network interface. The Model A lacked most of these options bar Econet due to being built without the necessary connectors and some of the required components.

The Model A was discontinued after the launch of the Acorn Electron.

Variants

Acorn released two versions of the Model A

  • ANA01 - The standard Model A
  • ANA02 - Fitted with the optional Econet interface chips and socket

Characteristics

While physically identical, the Model A lacked a number of internal components and interfaces.

Internal

  • 16K of RAM instead of 32K (The empty spaces were fitted with sockets to simplify upgrades)
  • 6522 VIA Chip

Rear interface sockets

  • RGB port
  • Serial port
  • Analogue port

Underside interface sockets

  • Tube
  • User port
  • Centronics (printer) port
  • 1MHz Bus

ModelA Motherboard.jpg

All of these components could be installed to bring the machine up to full Model B specifications. Sockets were present on the board to allow easy installation of the missing chips, and it is quite difficult to find an unmodified Model A now.

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