Planet Shelezyak - ADDITIONAL RAM CACHE.

 ▒ ▒ ▒▒ ▒ ▒ ▒ ▒ ▒ ▒ ▒▒▒ ▒▒
 ▓ ▓ ▓ ▓ ▓ ▓ ▓ ▓ ▓ ▓ ▓ ▓ ▓ ▓
 ░░ ░ ░ ░░░░ ░░ ░░░ ░░░ ░
 ▓ ▓ ▓ ▓ ▓ ▓ ▓ ▓ ▓ ▓ ▓ ▓
 ▒ ▒ ▒▒ ▒ ▒ ▒ ▒ ▒▒▒ ▒ ▒▒


         ─── ANOTHER ───
       ─── PLANET SHELEZYAKA ───

 We bring to your attention an article from
magazine DEJA VU #7. 


 V. Kovalev

            ADDITIONAL RAM

===========================================

               Hello All!

   PRUSAK brought his new app to me here
paratal lotion, it’s on his Pen-
tagon 512, and so far there have been no glitches...

==========================================================


 The essence of this device is that
instead ofROM BASIC 128 and TR DOS sub-
is RAM type 62256 (32K), which is emulated
lyrates the ROM. Thus, instead of boring
menus 128 BASIC can be supplied with your own
military commander or anything else, as well
use your own versions of DOS.
For example, I have already collected a collection of DOS's.
   For installation you need:
a) Check the method of decrypting the key port
viatures #FE. It must be selected at A0=0
and A7=1. Otherwise, it is necessary to
update the computer.
b) Required RAM 62256-1pcs, 15ZZLL1-2pcs,
15ZZLN1, 15ZZLIZ, 15ZZIR23.

   This diagram is provided for machines with ROM
27512. Modify the circuit for other types of ROM
It's not difficult, but it won't be given.
The diagram is shown in Fig. 1


RAM 62256 (32K)
                       ┌─┐ ┌────┐
/WR ──────────────────┤1├──────────O/WR │
bitO ──────────────────┤ │┌─────────┤A14 │
                       └─┘│ │ │
                       ┌─┐│ ┌───────O/CS │
                +Up ───┤&││ │ /RD ─O/OE │
bit2 ────────┬─────────┤ ├┘ │ │ │
DOS ────────┼─────────┤ ││ │
/ROMCS ──────┼─────┐ └─┘ │ │ │
             │ │ ┌─┐ │ │ │
        ┌─┐ │ ┌─┐ └─┬─┤1├──┘ └────┘
bit1───┬┤1├──┼─┤&├─┬─┼─┤ │
Хbit───┼┤ │ └─┤ │ │ │ └─┘ ROM 27512
#7FFD │└─┘ ┌┤ │ │ │ ┌────┐│┌─┐ │└─┘ │ └──┐ ┌─┐ 22│ │
       └┤1├───┘ │┌─┐ └─┤ ├───────O/CS │
DOS ────┤ │ └┤1O───┤ │ │ │
        └─┘ └─┘ └─┘ │└────┘

                  Fig.1


   Now I will describe the principle of operation of the circuit.

   bitO,bit1,bit2 are the bits of the port, on which
which this device will be hung (port
126 or #7E). Bit 0 enables/disables
write to RAM. Bit 1 turns on/off the sa-
mo RAM. Bit 2 is forced into RAM
bank corresponding to DOS. This is necessary
so that when installing DOS in RAM
it was possible to record it without any problems. RAM
turns off if 48 BASIC is running. This
achieved by setting the 4th bit of the port
#7FFD to the device diagram.

   Now about the implementation of port #7E. Port de
barks on one 15ZZLL1 and 15ZZIR23. Scheme
shown in Fig. 2




 ┌─┐
                                ┌─┤1O── b0
                     ┌───┬──┬──┐│ └─┘
          D0 ───┤D0 │RG│Q0├┘ ┌─┐
          D1 ───┤D1 │ │Q1├──┤1O── b1
          D2 ───┤D2 │ │Q2├─┐└─┘
          D3 ───┤D3 │ │Q3│ │┌─┐
          D4 ───┤D4 │ │Q4│ └┤1O── b2
          D5 ───┤D5 │ │Q5│ └─┘
          D6 ───┤D6 │ │Q6│
          D7 ───┤D7 │ │Q7│
                     ├───┤ │ │
        ┌─┐ ┌────/C │ ││
A0 ──┤1├┐ │ ┌──o/CS│ │ │
A7 ──┤ ││ ┌─┐│ ┴ └───┴──┴──┘
        └─┘└─┤1├┘
        ┌─┐ ┌┤ │
IORQ ──┤1├─┘└─┘
WR ──┤ │
        └─┘
                  Fig.2

 Inverters at the register output are supplied
so that when you turn on the computer
modification was turned off. Enable some
-or a bit can be written by writing a unit into it.
So, for example, installing DOS and BASIC on the computer
the assembler will look like this:
DI
LD A,%00000111 ;forcefully enable
 ;DOS and recording resolution,
                ;moreover, bit 1 can be omitted
                ;install.
OUT (126),A
LD HL,DOS_ADRES ;at this memory address
 ;must be DOS.
LD DE,0
LD BC,16384
LDIR

LD BC,#7FFD
IN A,(C)


PUSH AF ;save port value #7FFD
 ;(if you can’t read it, then
          ;SORRY).
LD A,%00000000
OUT (C),A ; install ROM with 128 BASIC
 ;(because with BASIC 48 additional
          ;nitial RAM is disabled).
PUSH BC
LD A,%00000011 ; enable recording resolution
 ;in RAM and RAM itself.
OUT (126),A
LD HL,BASIC_ADRES ;sent from memory
 ;BASIC 128 in RAM.
LD DE,0
LD BC,16384
LDIR
LD A,%00000000 ; turn off RAM (if desired
 ;you can set the first
                ;bit).
OUT (126),A


POP BC
POP AF
OUT (C),A ;restore the port value
 ;extensions.
EI
RET



 The remaining bits of port 126 (bit3-bit7) in
are not used in this modification, but when
When sending numbers to the port, it is better to zero them. U
I'm hung up on them: on bit 3- on/off
shadow RAM (0-on), on bit 4 - on/off
writes to shadow RAM (0-off), on bit 5 -
on/off 512K (0-on). Putting or removing
inverters, you can select the necessary con-
figuration when turning on the machine.

   And finally, I give the layout of the mic pins
RAM 62256 circuits:

 ┌───┬───┬───┐
 10─┤A0 │RAM│D0 ├─11
            9─┤A1 │ │D1 ├─12
            8─┤A2 │ │D2 ├─13
            7─┤A3 │ │D3 ├─15
            6─┤A4 │ │D4 ├─16
            5─┤A5 │ │D5 ├─17
            4─┤A6 │ │D6 ├─18
            3─┤A7 │ │D7 ├─19
           25─┤A8 │ │ │
           24─┤A9 │ │ │
           21─┤A10│ │ │
           23─┤A11│ │ │
            2─┤A12│ │ │
           26─┤A13│ │ │
            1─┤A14│ │ │
              ├───┤ │ │
           20─O/CS│ │ │
           22─O/OE│ │ │
           27─O/WR│ │GNDX─14
              │ │ │UccX─28
              └───┴───┴───┘

Port layout 126 DEC; #7E HEX

bitO - write to RAM (1-yes,0-no);
bit1 - RAM (1-on, 0-off);
bit2 - DOS forced (1-on, 0-off);
bitЗ - shadow RAM (0-on, 1-off);
bitХ - writing to shadow RAM (1-on, 0-off)
bitS - 512K Mode (1-off,0-on);
bitb - reserved;
bit7 - reserved.





              *  *   *