Hardware - About connecting shadow RAM.

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│░░░░░░░░░░░░░░ SHADOW RAM ░░░░░░░░░░░░░░│
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(C) Hamer MDM 221-8365
                                          
   Recently I, first at Nikiforov’s, and then
so I made a small one for myself, but very
a handy little thing called Shadow RAM.
The basis was taken from the diagram published
Naya in  17th Spectrofon. It says
about connecting 2 kilobyte RAM, but
this seemed to us very little and we re-
They decided to set themselves as much as 32 kg. BSpectro-
fon  by the way, we talked about connecting
this gadget together with COVOX, but
since not all of these COVOXes have
then the diagram had to be modified a little.    
   So, the diagram:                          
                                          
                    TM2 ┌───┐1                      
     _____ 4┌─┬────┐ 3│1 ├──── A14               
     RESET ──────┤R│ │ BLOK ┌─┤ │2                      
                2├─┤ Q├──── │ │ ├──── A15               
        A7 ──────┤D│ │5 │ └───┘                       
                3├─┤ │ │4┌───┐┌──┤C│   _│6        └─┤  1│6    ______            
       ___    │ 1├─┤   Qo────────┐ 5│   ├──── CS_RAM            
       MAG ───┼──┤S│    │        └──┤   │                       
              │  └─┴────┘    ЛЛ1    └───┘                       
              │   ┌───┐12   ┌───┐9    ____                      
              │ 11│1  ├───┐8│1  ├──── IORQ                      
              └───┤   │13 └─┤   │10                             
                  │   ├──┐  │   ├──── A2                        
        __        └───┘  │  └───┘                               
        RD ──────────────┘          ┌───┐1                      
                         _______   3│1  ├─── BLOK               
                         CS_ROM0 ───┤   │2   ______             
                                    │   ├─── CS_ROM             
                                    └───┘                       
                                                                
   Сигнал  BLOK  служит для блокировки об-
ращения  к  ПЗУ  во  время работы теневого
ОЗУ.  Сигнал  /CS_ROM  подключается к про-
воднику,  ведущему к 20-ой ноге микросхемы
ПЗУ,  которую  (ногу)  нужно  отделить  от
платы,  сигнал  /CS_ROMO  заводим на отор-
ванную  20-ую ногу ПЗУ'шки.  Если TR-DOS у
вас  прошита в той же ПЗУ, что и  BASIC то
вам  повезло,  иначеwith TR-DOS ROM
you will have to do the same as with the main
(adding another OR element).  If in
your computer has the ability
lock ROM's through the system connector,
or some other way, then there will be no need to get tired
pour in additional mikrukha LL1.  B
Profi is the 6th pin of the switch
ROM is on the top board, but for its use
use it is necessary that everything is 64K
The ROMs were in one microchamber on the bottom
board, then, by the way, the block is on the top
board can be used for our
RAM.  In Byte there is also such an opportunity
there is, but I don’t remember which leg it is.
connector                                  
   Now about the RAMs themselves.  I'll give you a
chip slot for 32k:                 
                                          
 ┌--┬┬--┐                  
           A14 -┤1 └┘28├- Vcc             
           A12 -┤ ├- /WE             
            A7 -┤ ├- A13             
            A6 -┤ ├- A8              
 A5 -┤ ├- A9              
            A4 -┤ ├- A11             
            A3 -┤ ├- /OE             
            A2 -┤ ├- A10             
            A1 -┤ ├- /CS             
            A0 -┤ ├- D7              
            D0 -┤ ├- D6D1 -┤ ├- D5              
            D2 -┤ ├- D4              
           GND -┤14 15├- D3              
                └------┘                  
                                          
   The 16K mikruha does not use the 1st
leg.  The /OE signal must be connected to the signal
processor /MREQ (19th processor leg, or
B18 in syst. Profi connector).  Signal /CS -
to the /CS_RAM signal in the circuit of this device.
Signal /WE - to processor signal /WR (22
processor leg, or B21 in system. connector
Profi).  Conclusions A0-A13 and D0-D7 to the corresponding
current pins of the processor, or system. 
connector  If you are the happy owner
32K RAM, then pin A14 of the RAM follows -
lead to A14 (27th leg) ROM, in which
flashed 128th BASIC, or to A31 system. times-
Profi connector and now you have the opportunity
It is possible to switch shadow RAM banks like this
the same as the banks of the usual 128th ROM
res 4th bit of port #7FFD.                 
  But all this is bullshit if there is no opportunity
fly into shadow RAM using MAGIC culture-
but without any glitches.  And the whole joke is -
The problem is that this device does not have time to transfer
switch memory with the arrival of the /NMI signal.
Here's another diagram for this:                
                                          
 MAGIC+ ___             
           ┌╥┐ ┌------- NMI║/│                        
            / │ ___             
    ┌------/ ---o------- MAG             
   -┴- │                        
           ┌---┐ │ │/│ ____            
     +5V o-┤ ├-o-┤ ├--- WAIT            
           └---┘ ││                    
           1OKOhm KD5O2                   
                                          
   The diode can not be installed on those machines
on which the /WAIT signal is not generated -
Xia, for example, on the Pentagons, but on Profi
he is desirable.  By the way, it will be better on Profi
if the /NMI signal on the upper board is negative
from the circuit on the system connector itself. 
   Now about the schemes: mikruhi TM2  and LL1
you can take any series (155, 555, 1533)
Signals, designation in text with icon
"/" are inverse.  Micro RAM - 32K:  43256,
51256, 62256, 16k -  62128, etc.      
   Now about programming this application.
bambasa: shadow RAM is turned on with the command
IN A,(#FB)  , and returns to the original
state by command  IN A,(#7B) (as in
ZX-LPRINT III)                            
   And finally about the software. Everyone knows
Alexander Nikiforov has already adapted it to
this is the case CONVER COMMANDER  (only 32k RAM),
PERFECT COMMANDER, MONSTER COMMANDER, FPM
COMMANDER, STSS.1 (16k RAM) and continues
continue to adapt.  Support-
there is shadow RAM and demo OVER THE TOP , where
it hosts COVOX PLAYER, for more
that sound.