--- Tony Duell <ard_at_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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Received on Tue Nov 21 2000 - 04:48:36 GMT