system connector

13 Jul 01 15:34, Nik Aleksandrovich wrote to All:

NA> HEY, happy owners of Scorpios, who have the pinout of the subject on
NA> at the moment, it is very necessary, I would like to collect an open arch at least according to
NA> standard, if available, please send it, in any (readable ;) video.

* Originally in HARDWARE.ZX
* Crossposted in REAL.SPECCY
* Crossposted in ZX.SPECTRUM
* Crossposted in ZX.TALKING
* Crossposted in SPB.SPECCY

This is a file of happiness. It needs to be checked for viruses, re-encoded into different
encodings, formatted, archived, copied onto four floppy disks,
cut onto a CD, burned to tape, put on a BBS, printed on a dot-matrix/inkjet/laser printer, send to all echo conferences and soap
to everyone you know.
This file began traveling around the world before ZXNet and
ZX-Spectrum appeared. It was pumped out of space by followers of Tantric Buddhism and
recorded on soft (5.25) discs. So Clive Sinclair discovered him, he
did everything as written and his company first got rich and then went bankrupt.
If you do everything that is written here, then there will be happiness, otherwise there will be trouble.
One woman did everything she needed, and her breasts grew. And one
man laughed and erased this file, so his chest also grew.
Scientists from Uruguay calculated that by the year 2000 this file will bypassaround the globe 512 times, if everyone who receives it does everything correctly.
Changes cannot be made to this file, because the ZX-Spectrum computer architecture is encrypted in it, and there is also a checksum verification code. One boy wanted to insert his copyright here -
"Rysified by CrAzY Killer" - but forgot how to switch registers and this
was saved.
And one housewife, although she worked on a kaya under IS-DOS, did everything
correctly and a cool hacker came to her, hacked the security and they got married.
And John T. forgot his administrator password, and he was advised to work with
this file. He tried it and liked it so much that he no longer wanted to be
an administrator.
This file is distributed as FREEWARE, no individual or
organization has the right to charge a fee for its distribution.
The file is supplied on an "AS IS" basis.
ANYTHING NO WARRANTY IS INCLUDED OR PROVIDED.

SYSTEM BUS OF THE ZX-Spectrum COMPUTER (ZX-BUS)
=================================================

System connector of the ZS-Scorpion computers (manufactured
by Scorpion) and the KAY computer (manufactured by Nemo).

All signal designations are given according to the diagram. ZS-Scorpion yellow board.

contact signal contact signal

1A A14 1B A15
2AA12 2B A13
3A +5V 3B D7
4A /DCDOS (3) 4B /CSDC (1)
5A см. примечание! (2) 5B TURBO (KAY!) (6)
6A GND 6B D0
7A GND 7B D1
8A RAS (4) 8B D2
9A A0 9B D6
10A A1 10B D5
11A A2 11B D3
12A A3 12B D4
13A /IORQCE 13B /INT
14A GND (KAY!) (7) 14B /NMI
15A /CSROMCE 15B /HALT
16A RS (KAY!) (5) 16B /MREQ
17A 17B /IORQ
18A 18B /RD
19A /BUSRQ 19B /WR
20A /RES 20B
21A A7 21B /WAIT
22A A6 22B
23A A5 23B
24A A4 24B /M1
25A /CSROM 25B /RFSH
26A /BUSAK 26B A8
27A A9 27B A10
28A A11 28B +5V (KAY!) (7)
29A +5V (KAY) (7) 29B +12V (KAY!) (7)
30A GND 30B GND

Примечания:

(KAY!) -- the signal is connected only in the computer KAY

(1) -- connecting page 0 of RAM (0xc000..0xffff in
zx-48kb mode) instead of ROM. The signal is available only in
Scorpion and KAY computers.

(2) -- the contact has different purposes in different models
of computers. In the early
ZS-Scorpion computer it is marked as RESERVE. Later
it was used to supply +12V power to expansion boards
. On turbo boards (green) there is an unused
contact. In the KAY computer, but this contact outputs
a clock frequency signal of 14 Mhz.

(3) - a signal indicating the connection of ROM and ports
Beta-Disk interface.

(4) - in the Scorpion computer this is both a clock frequency signal
of the processor, and an inverted and delayed signal
/RAS controlling dynamic RAM (according to the scheme
Leningrad). In turbo versions of ZS-Scorpion, the signal is not synchronous with the processor clock frequency. On a
KAY computer, this signal is not synchronous with
the processor clock frequency and is an
inverted /RAS signal. The frequency is always 3.5Mhz.

(5) - the signal is available only in the KAY computer. This is the output
of register 7FFD responsible for the ROM bank (basic-128 or
basic-48). Can be controlled by an external device.

(6) -- the signal is set to 1 when the turbo mode is enabled
. The output is an open collector type, that is
the expansion device can forcibly disable
turbo mode. The signal is used only in KAY.

(7) -- in the ZS-Scorpion computer the contact is not used,
is used only in KAY.

The /CSDC, /IORQCE, /INT, /NMI, /CSROMCE and /WAIT
signals have a high output impedance and can be controlled
by devices connected to the bus (expansion slots).
In general, external devices should not use these signals
to receive any information, that is, for them these are
outputs - for example, in the latest version of KAY, the /IORQCE
signal is made as an input.
A typical circuit on a computer board for all of
the listed signals:

/CSDC_out /CSDC
/IORQ /IORQCE
/INT_out 300-600 ohms /INT
/NMI_out -------RRRRRR------ /NMI
/CSROM /CSROMCE
/WAIT_out /WAIT

On the left are the sources, on the right are the signals going to the expansion slot
and simultaneously to the processor, ROM, I/O ports
(located on the computer board) or other devices.

The /DCDOS signal canused by expansion cards
only as an input -- it tells external devices that
only ports in the address space
of the Beta-Disk interface should be decoded. In general, in the original version of the Beta-Disk controller, it was connected to the ZX-Spectrum as an expansion board, but no /DCDOS signal was provided.
The /IORQ signal was connected to the controller, and /IORQCE was returned to the board
, processed exclusively by the controller.

CONNECTING EXTERNAL DEVICES TO THE SYSTEM BUS.
=================================================

Several general recommendations:

If the device should not respond when the
Beta-Disk interface is activated, connect the /DCDOS signal to the address decoder
along with the address signals.

Never connect the /RD or /WR signal to the address inputs
of the decoder, if the device supports writing and reading
simultaneously: signals /IORQ, /RD and /WR in the processor
are not switched simultaneously and false
alarms are possible. The best option is a combination of IORQ+RD for reading
and IORQ+WR for writing. To suppress the reaction of devices on the board
(especially for the KAY computer), you must force
set the /IORQCE signal to the log. 1. when decrypting the address
of your device (read more about the address). In the event
if on the port decoderIf /RD or /WR
I/O signals are not used, then the /M1 signal must be used.

The address in the device must be decrypted BEFORE THE DEVICE IS ACTUALLY ACCESSED (determined by the /IORQCE or
/MREQ signals), especially when using the /IORQCE or
/CSROMCE signals to block devices on the board.

Typical decoder circuit:

DD2.2
DD2.1 +---+
DD1 /IORQ +---+ /RD --+1 |
+----+ /MREQ --+1 | | +-- /read
A0, A1... A15 ---+0DC | | +-------+ |
Ax -----+1 o-----+----+ | +---+
Ay -----+2 | | +---+
| | | +---+
/DCDOS ------oE | +-----oE >|
+----+ | +---> /IORQCE /CSROMCE
+5V +---+x |
+---+
DD3

the node that generates the /write
signal is built in a similar way (like the reading node on
DD2.2), only instead of the /RD signal /WR is used.

DD1 decoder type 555ID7
DD2 logical element "OR" type 555LL1
DD3 buffer with powerful outputтипа 555ЛП8

Somehow Wednesday October 17, 2001 at 20:05:26 lil
Kirill Frolov to Nik Aleksandrovich on the topic of system connector

KF> DD1 decoder type 555ID7
KF> DD2 logical element "OR" type 555LL1
KF> DD3 buffer with a powerful output like 555LP8
Since when did LP8 become a buffer (and even with a powerful output type)?

SAYO:NARA, DO:ZE O-GENKI-DE, Evgeny Poddubny.

@ ZXNet 500:4232/1.777 | Fidonet 2:5045/78.777

EP> Since when did LP8 become a buffer (and with, like, a powerful output)?

From the very beginning it was like that. :-/