--- Tony Duell <ard(a)p850ug1.demon.co.uk> wrote:
Much of the random logic in the 380Z (address
decoding, video timing
decoder, etc) is done in small bipolar PROMs. These
look a bit like TTL
devices, and may even have 74xxx numbers.
The blank chips are identical (both are 74S2872,
256*4 bit PROMs), but
the programming is different.
AH! Controrary to what I was led to believe. I never
new there were 74xxx coded proms. I do now :)
)
In what format? Electronic? (i.e. easily
sharable?)
No, on paper. I don't have a scanner, heck, I only
have a text display on
my PC, so I don't ever use electronic manuals. Quite
apart from the fact
that paper ones are a lot more portable.
Shame :(
The official _commented_ source listing would have
been interesting for
the comments. I know these can be recreated, but...
Fair enough. I'll keep my eyes open for it...(sad
optimism)
The schematics show that the COS ROMs (on the CPU
board) are 3 rail ones,
needing +5V, +12V and -5V. A lot of modern
programmers can't handle these
(the last 3-rail EPROM that I came across was the 2K
byte TMS2716, which
is _ancient_).
OH! Something else that became obsolete before I
started taking things apart...(I'm only 23)
That would explain rather a lot. I'll have to build
me an eprom dumper then.
I'll get one of them 24 bit (8255 based) ISA IO cards
from maplin (about 25 quid ISTR) and make one up.
I'll probably be needing some data on the chips then -
normally I would generate the -5v with a simple
switched-capacitor or 'flying capacitor' inverter
arrangement - but if it needs more than a couple of
millamps, i'm gonna need a -5v psu as well :-/ Hmmm!
How about the one in the RML380z! I will get the
contents of those roms - even if it kills me...
> Are you
sure this is a standard RML disk
controller?
> I can't find any LED
> on the schematics, and I don't remember there
being
> one when I looked
> inside my machine. The standard disk controller
is
> one card that fits
> onto the 50 way 'bus' ribbon cable, and which
> contains a 1771 disk
> controller (Single density only) and a
8251-based
serial
port (device SIO-4)
Um, no! I know nowt about this box - I'll check
the
disk controller very carefully tonight. Its
software
is certaining interesting - very wacky code,
quite
a
What softwre? and for that matter, you mention a
disk ROM, which I have
never heard of...
The disk cotnroller schematic I have shows the
following chips (only).
Location Type
AQ 74LS244 (address buffer)
AR 74LS245 (data buffer)
AP 74LS244 (Control line buffer)
BR 74LS138 (address decoder)
BP 74LS32
CP 74LS02
BU 74LS393 (clock divider)
DP 4020 (more clock division)
CQ 74LS32
ES 74LS74
DQ Z80A-CTC (baud rate, timing generator)
ER 8251 (serial USART)
CR 74LS00 (?)
DU 74LS123
AV 1488 (RS232 driver)
BV 1489 (RS232 receiver)
CS WD1771 (disk controller)
BT 74LS157
AT 7416 (disk output driver)
BU 74LS244 (disk input receiver)
CT 74LS193
DT 74LS42
CU 74LS96
ET 74LS00
EU 74LS08
No RAM, ROM, or CPU.
After checking it out some more it has:
dated '83, where most of the box is '79
Z80A CPU,
Z80 CTC,
8Kbyte EPROM (HUUUUGE!)
MK4802 2Kbx8 SRAM
MK3884N which is a mostek sourced Z80SIO-a-like POSH!
MB8877a which I believe is a 5voltonly WD1793
i.e. A double density controller. There are obviously
other devices - I just didn't note them.
Looks like a more advanced double density dual drive
controller then :) I wonder if it's double-sided as
well??? I'll have to check my WD1793 docs.
So! Have I got something a bit different then?
Dave.
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