is supplied either ready built, or as a kit. A number of options are
FDC and Winchester controller
(2797 or 2793
FDC Controller, depending upon system)
The board or kit is supplied with the appropriate combination of options as
ordered. The PCB is the standard 8″ square, with the usual Map 80 blue resist
and high quality. Kit assembly is quire straightforward and the instructions
are reasonably clear – there is a separate assembly manual which I didn’t
receive but a phone call to Map soon solved the problem.
There are 22 Links on the board, some of which are not needed for standard
configurations and a 20 way link header to be wired up if one wants the SIO
and/or CTC facilities. Details of the link functions and also the changes
necessary to accommodate the 2793 controller, if the board is to be used as a
Lucas/Nascom compatible FDC, are provided.
A slight disadvantage is that the instructions are not very clear on which links
are needed for particular uses – my boards have Links 2 (a-b),3 3 (a-b),6 (a-m).
13 (a-m), 14 (a- 13n) 15 (a-c), 16 (COM-E), 17 (b-c),18 (c-6, d-5), and 21
(a-Clk). Map will supply details of modifications required to read odd disk
formats with bad side 2 flags, which might be necessary if you wish to use
their Format transfer program. No details are provided of the crystal
frequencies or types required for on-board frequency generation.
The SIO and CTC seem to be standard implementations using the Z80A CTC and SIO
chips. The circuitry around the 2797 seems to be almost identical to that used
and the RS485 interface is provided by differential line driver and
receiver (75174/75175), in contrast to the R5232 interface which uses the
conventional 75188 and 75189 types.
My main use for the MPI is as a Floppy/Winchester controller and both the ready-built
and kit versions have performed without trouble with a wide range of other
boards from Nascom, Map and Gemini. In particular, the combination of the MPI
with TEAC compatible drives and the Map version of CP/M Plus provides fast,
quiet disk access – I hate noisy computers!
As I sometimes need to copy disks with peculiar formats, the small modifications
to the board for this purpose are easily made. I don’t need to use either the
SIO or CTC functions (although they are implemented on one of the boards) – I
use the Serial o/p on the Map or Gemini CPU board for this.
The fully-assembled version with FDC, CTC and SIO options is possibly a bit
pricey at £195 + VAT but money can be raved by building the kit yourself – not a
long job – possibly a couple of evenings. Host users need only the FDC/SASI
version and this is quite a bit cheaper. I haven’t seen an up-to-date price
list from Gemini or Map but suspect that the ready built FDC/SASI is about the
same price as the
(£145, in the last price list I saw from
Gemini). It would be worth contacting Map to see what their current prices are
I can thoroughly recommend this product for anyone contemplating upgrading an
80-BUS system even if they already have the Gemini
FDC, since it will enable
them to take full advantage of higher access speeds and quieter operation if the
newer TEAC-compatible drives are used. [Ed. – alternatively readers may like to
make the the
modifications shown elsewhere in this issue.]