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ZX Spectrum emulator for TS2068 and Timex FDD

7 messages · 2004-07-13 → 2004-07-21 · Yahoo Group era · View archive on archive.org

Participants: Jarek Adamski, aralbrec, Johnny Red, Jack Boatwright

Preserved from the Timex/Sinclair 2068 Yahoo Group (2001–2019), which is no longer online. Text reproduced from the archive.org archive; email addresses masked.

Messages

1. ZX Spectrum emulator for TS2068 and Timex FDD

Jarek Adamski · Tue, 13 Jul 2004 12:38

Hello,

Could someone explain me, how the ZX Spectrum
emulator works? The cartridge slot in TS2068
differes from TC2068 - has /RFSH in place of
/ROMCS. So, the only way to page ROM in HOME
bank is to generate /BE=0.

Also, Timex Interface M-397 disables the
internal ROM with /ROMCS=1 for ZX Spectrum bus,
what should be converted to /BE=0 by the
twister board (in combination with A14, A15
and pehaps duplication of #F4 port).

So, when both the emulator cartrige and the
Timex Interface disable the internal HOME ROM,
which one provides data to data bus ????
At the first sight both should.

In other words, how the external interface can
disable the emulator memory (that disables
already HOME ROM)?


In TC2068 emulator disables HOME ROM pulling
up (+5V) the /ROMCS-cartridge-slot line (just
ROM pin). Then external interface disable
cartride memory with /ROMCS-edge-slot line
(not the same as the /ROMCS-cartridge-slot
line they are separated by diode), connected
to /BE pin in cartridge slot.


Or, perhaps, using Timex Disk System requires
internal TS2068 upgrade?

-- 
Jarek Adamski

2. Re: [ts2068] ZX Spectrum emulator for TS2068 and Timex FDD

Johnny Red · Tue, 13 Jul 2004 17:48

Well I don't know how it works, but I know that TC2068 works with TS2068
cartridges.

TS2068 do not need an upgrade to work with FDD.
It only needs the twistor because of the "remaping" of the signals in the
edge connector.

Johnny Red

on 07/13/2004 13:38, Jarek Adamski at [email] wrote:

> Hello,
> 
> Could someone explain me, how the ZX Spectrum
> emulator works? The cartridge slot in TS2068
> differes from TC2068 - has /RFSH in place of
> /ROMCS. So, the only way to page ROM in HOME
> bank is to generate /BE=0.
> 
> Also, Timex Interface M-397 disables the
> internal ROM with /ROMCS=1 for ZX Spectrum bus,
> what should be converted to /BE=0 by the
> twister board (in combination with A14, A15
> and pehaps duplication of #F4 port).
> 
> So, when both the emulator cartrige and the
> Timex Interface disable the internal HOME ROM,
> which one provides data to data bus ????
> At the first sight both should.
> 
> In other words, how the external interface can
> disable the emulator memory (that disables
> already HOME ROM)?
> 
> 
> In TC2068 emulator disables HOME ROM pulling
> up (+5V) the /ROMCS-cartridge-slot line (just
> ROM pin). Then external interface disable
> cartride memory with /ROMCS-edge-slot line
> (not the same as the /ROMCS-cartridge-slot
> line they are separated by diode), connected
> to /BE pin in cartridge slot.
> 
> 
> Or, perhaps, using Timex Disk System requires
> internal TS2068 upgrade?

3. Re: ZX Spectrum emulator for TS2068 and Timex FDD

aralbrec · Tue, 13 Jul 2004 19:32

Hi Jarek, 

>Could someone explain me, how the ZX Spectrum 
>emulator works? The cartridge slot in TS2068 
>differes from TC2068 - has /RFSH in place of 
>/ROMCS. So, the only way to page ROM in HOME 
>bank is to generate /BE=0. 

>Also, Timex Interface M-397 disables the 
>internal ROM with /ROMCS=1 for ZX Spectrum bus, 
>what should be converted to /BE=0 by the 
>twister board (in combination with A14, A15 
>and pehaps duplication of #F4 port). 


In the TS2068 there is internal memory 
which consists of the HOME bank, DOCK 
bank and EXROM bank, and external 
memory which is managed by /BE. 

It also has signals /ROSCS and /EXROM 
which are generated by the SCLD and are 
run to both the cartridge and the expansion 
interface.  /ROSCS is active whenever a memory 
access to the DOCK bank is occurring and 
/EXROM is active whenever a memory 
access to the EXROM is occurring.  In which 8k 
chunks the EXROM and DOCK are active is 
determined from the horizontal select register 
(port $f4) and bit 7 of port $ff. 

A cartridge Spectrum emulator simply maps 
itself into the bottom 16K of the DOCK bank 
by watching /ROSCS and A14/A15. 

>So, when both the emulator cartrige and the 
>Timex Interface disable the internal HOME ROM, 
>which one provides data to data bus ???? 
>At the first sight both should. 

Cartridges don't touch /BE. 

/BE disables all internal memory which includes 
the HOME bank, DOCK bank and EXROM bank. 
The SCLD will make /ROSCS and /EXROM inactive 
when /BE is low so there is no conflict. 

>In TC2068 emulator disables HOME ROM pulling 
>up (+5V) the /ROMCS-cartridge-slot line (just 
>ROM pin). Then external interface disable 
>cartride memory with /ROMCS-edge-slot line 
>(not the same as the /ROMCS-cartridge-slot 
>line they are separated by diode), connected 
>to /BE pin in cartridge slot. 

Yuck.  Did they really change the cartridge 
slot?  Jarek, are you able to document the 
cart connector on the TC2068 (And the 
spectrum connector on the back of the TC2068, 
may as well ask :-).  If Timex of Portugal did this, 
they did not understand the TS2068 design -- 
they've made something worse than what was 
there in the first place. 

>Or, perhaps, using Timex Disk System requires 
>internal TS2068 upgrade? 

No, the Timex FDD was sold here by an importer 
and only required a twistor board.  As you say, 
the /ROMCS signal can be simulated with /BE 
and logic on A13..A15. 

Both the TC2048 and TC2068 have all the 
same logic in their PAL SCLD, including ports 
$f4 / $ff for managing the DOCK, EXROM and 
HOME bank.  I suspect that the /ROSCS, /EXROM 
and /BE signals are also available on the PAL 
SCLD pins, even if they didn't make it to an edge 
connector.  In other words I don't think Timex of 
Portugal would have made significant changes to 
the TS2068's SCLD.  The fact that "TS2068 PAL" 
is printed on the SCLD used in the TC2048 and 
TC2068 might indicate they didn't make any 
changes at all.  I always suspected that the TC's
spectrum signal /ROMCS was actually /BE with 
some logic attached externally somewhere on 
the board.  But if what you are saying is correct, 
Timex of Portugal might have made some 
incompatible changes (and not for the better!). 

Alvin

4. Re: ZX Spectrum emulator for TS2068 and Timex FDD

Jarek Adamski · Tue, 13 Jul 2004 22:24

Hi Alvin,

--- In [email], "aralbrec" <aralbrec@i...> wrote:

> In the TS2068 there is internal memory 
This is clear to me.

> A cartridge Spectrum emulator simply maps 
> itself into the bottom 16K of the DOCK bank 
> by watching /ROSCS and A14/A15.
OK. The UK2086 dedicated Spectrum emulator
connects itself into HOME. I expected the
TS2068, too. While I see it impossible having
an TS2068 on my desk. (BTW I took the power
from external +5V/+12V PSU.)

> Yuck.  Did they really change the cartridge 
> slot?
Yes, see the schematics:
 http://www.zx.yarek.pl/computers/zx.ts2068/

These cartridge slot pins are not described:

Pin TS2068 TC2068
32  /RFSH  /ROMCS
33  /BE    DIS

Where DIS is a signal that disables cartrige
memory, also pulls up (with diodes not preset
on schematics) the /ROMCS and /EXROM (both
these lines have an ~680ohm resistors, like
the /ROMCS in ZX Spectrum). The DIS is also
available on edge slot - called /ROMCS on the
schematics.


> Jarek, are you able to document the cart
> connector on the TC2068 (And the spectrum
> connector on the back of the TC2068, 
> may as well ask :-).
OK, I will update the schematics in some free
time.

> If Timex of Portugal did this, they did not
> understand the TS2068 design -- they've made
> something worse than what was there in the
> first place.
Quite possible. :D


> No, the Timex FDD was sold here by an importer 
> and only required a twistor board.
Well, if the TI works with ZXROM placed in DOCK,
how it works with the TS HOME ROM (I mean the
TI ROM modified by Zebra). I will think about it.


> Both the TC2048 and TC2068 have all the 
> same logic in their PAL SCLD, including ports 
> $f4 / $ff for managing the DOCK, EXROM and 
> HOME bank.
Right. There's no use of DOCK and EXROM in TC2048,
the outputs are not connected. However I've added
128kB SRAM as DOCK+EXROM to one.

> I suspect that the /ROSCS, /EXROM and /BE signals
> are also available on the PAL SCLD pins, even if
> they didn't make it to an edge connector.
They are in TC2068 and UK2086 only.

> I always suspected that the TC's spectrum signal
> /ROMCS was actually /BE with some logic attached
> externally somewhere on the board.
/BE disables as active low, while the /ROMCS high.
There's no logic around /BE in TCs.

In TC2048 it is done so:


(TS2068 chip)---/ROMCS---[680ohm]----(edge)---(ROM)



While in TC2068 there are also a diode between
(real) edge slot and "(edge)" place on above
diagram. Second diode works on /EXROM:


(TS2068 chip)---/ROMCS---[680ohm]----+---(HROM chip)
                                     |
                            .---|>|--'
(/ROMCS aka DIS on edge)----+
                            `---|>|--.
                                     |
(TS2068 chip)---/EXROM---[680ohm]----+---(XROM chip)


Jarek Adamski

5. Re: [ts2068] ZX Spectrum emulator for TS2068 and Timex FDD

Jack Boatwright · Tue, 13 Jul 2004 21:12

In a conversation with Nazir Pashtoon the other day, he commented
that the TC (and presumably the UK2086) emulator did not work with
the TS straight away.  Nazir indicated (if I remember correctly)
that all it took to make it work with the TS was "changing a
wire".

Jack

----- Original Message ----- 
From: "Johnny Red" <[email]>
To: <[email]>
Sent: Tuesday, July 13, 2004 9:48 AM
Subject: Re: [ts2068] ZX Spectrum emulator for TS2068 and Timex
FDD


> Well I don't know how it works, but I know that TC2068 works
with TS2068
> cartridges.
>
> TS2068 do not need an upgrade to work with FDD.
> It only needs the twistor because of the "remaping" of the
signals in the
> edge connector.
>
> Johnny Red
>
> on 07/13/2004 13:38, Jarek Adamski at [email] wrote:
>
> > Hello,
> >
> > Could someone explain me, how the ZX Spectrum
> > emulator works? The cartridge slot in TS2068
> > differes from TC2068 - has /RFSH in place of
> > /ROMCS. So, the only way to page ROM in HOME
> > bank is to generate /BE=0.
> >
> > Also, Timex Interface M-397 disables the
> > internal ROM with /ROMCS=1 for ZX Spectrum bus,
> > what should be converted to /BE=0 by the
> > twister board (in combination with A14, A15
> > and pehaps duplication of #F4 port).
> >
> > So, when both the emulator cartrige and the
> > Timex Interface disable the internal HOME ROM,
> > which one provides data to data bus ????
> > At the first sight both should.
> >
> > In other words, how the external interface can
> > disable the emulator memory (that disables
> > already HOME ROM)?
> >
> >
> > In TC2068 emulator disables HOME ROM pulling
> > up (+5V) the /ROMCS-cartridge-slot line (just
> > ROM pin). Then external interface disable
> > cartride memory with /ROMCS-edge-slot line
> > (not the same as the /ROMCS-cartridge-slot
> > line they are separated by diode), connected
> > to /BE pin in cartridge slot.
> >
> >
> > Or, perhaps, using Timex Disk System requires
> > internal TS2068 upgrade?
>
>
>
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6. Re: ZX Spectrum emulator for TS2068 and Timex FDD

Jarek Adamski · Wed, 14 Jul 2004 15:07

Jack Boatwright wrote:
> In a conversation with Nazir Pashtoon the other day, he
> commented that the TC (and presumably the UK2086)
> emulator did not work with the TS straight away.  Nazir
> indicated (if I remember correctly) that all it took to
> make it work with the TS was "changing a wire".
Yes, exactly. A track must be cuted from pin 33 (/BE,
but not connected to SCLD in TC, but as /ROMCS on edge
slot) and soldered to pin 35 (/ROSCS).

Also, for safety, track going to pin 32 (/RFSH) must be
cuted (as in TC2068/UK2086 this disables the HOME ROM).

However, this way the HOME cartridge becomes DOCK
cartridge and OUT 244,3 is required to make it working.

I've just made it and it works.
So now I work on an EPROM with code that searches for
ZX ROM in DOCK, then in HOME and pages the original
TOS code when found, while the modified by Zebra (for
2068 ROM) when not.


Jarek Adamski

7. Re: ZX Spectrum emulator for TS2068 and Timex FDD

aralbrec · Wed, 21 Jul 2004 18:13

--- In [email], "Jarek Adamski" <zx@y...> wrote:

> --- In [email], "aralbrec" <aralbrec@i...> wrote:
> 
> > In the TS2068 there is internal memory 
> This is clear to me.

Yeah, I know :-)  When I write a post, about
1/3 is aimed at the person I reply to, 1/3
is aimed at everyone else and 1/3 is me
talking to myself.

Thanks for the details on the TC cart slot.

Alvin

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Disk & floppy systems (Larken, AERCO, Oliger) · Spectrum emulation & software