Specifications
3000
A3000
expansion
Internal expansion
DANGER
DANGEROUS VOLTAGES ARE EXPOSED INS1DE
THE CASE OF THE COMPUTER WHEN THE
COVER IS REMOVED. THE COMPUTER SHOULD
BE DISCONNECTED FROM 'THE MAJNS SUPPLY
BEFORE THE COVER IS REMOVED.
The following internal upgrades are currently available
for the A3000 computer:
• User port / MIDI interna1 expansion card
• 1 Mb Ram upgrade
• Serial port
• Econet module
Interface
The electrical signals available on the internal
expansion are a subset of those described in 'A Series
Podules', available from Acorn Customer Service on the
SID system (Doc Ref 0310101) or as an Application
Note.
The connection is via two 17-way 0.1 inch pitch
connectors. Expansion cards should use 0.025 in
square pin headers.
The interface is configured as 'Podule 1, Module 1'.
Expansion bus connectors
Pin no.
SK3
SK11*
1
+5v
0v
2
PWE*
+5v
3
PS1*
PRE*
4
CLK2
PRnW
5
LA[2]
LA[4]
6
LA[3]
LA[5]
7
BD[0]
LA[6]
8
BD[1]
LA[7]
9
BD[2]
0v
10
BD[3]
LA[8]
11
BD[4]
LA[9]
12
BD[5]
LA[10]
13
BD[6]
LA[111
14
BD[7]
LA[12]
15
RST*
LA[13]
16
0v
PIRQ*
17
+5v
0v
Note: Pin 1 is at the right hand end when viewed from the
front of the computer.
Power supply
The maximum power available from the +5V rail is
600
mA. The maximum dissipation inside the case Js 0.5W
(100mA).
5
-
way
connectors
There are two 5-way 0.1 inch connectors fitted to the
main circuit board:
Pin no.
SK8
SK9
1
2
3
4
5
C[01
C[1]
Br
IORQ*
IOGTt*
0v
REF8M
PFIQ*
Ms[1]*
+5
Note: Pin 1 is at the righthand end, when viewed from
the front of the computer.
N.B. C[0] and C[1] are used as the 1IC bus.
It is recommended that the load on each signal does nct
exceed 3HCT gates or that stated in 'A Series
Podules'. Any upgrade must be able to drive at least 7
HCT and 3 TTL loads on the data bus.
Mechanical
The rear panel required is shown in the drawing at the
back of this manual. The size of the User Port / MIDI
expansion card PCB and position of the connectors is
also shown in the drawing included at the back of the
manual.
User port / MIDI expansion card (
UPM)
Introduction
The A3000 User Port / M1DI expansion card fits inside
the computer, and provides:
• An 8-bit User port, largely compatible with the User
Port interface on the BBC Model
B
and Master 128
computers (and with the User Port on the
Archimedes I/O expansion card)
• MIDI (Musical Instrument Digital Interface), with IN,
OUT and THRU connections, compatible with the
International MIDI Association specification.
Main components
• 65C22 VIA for the User Port
• 2691 UART for the MIDI
• 27128 EPROM containing firmware and ID byte.