On-Line #35 05 мая 1996

Железо

Mosaic - expanding ports ZX Spectrum.

(C) ROMIK


   Recently (in ONLINE 30 .. 33, and not only in
ONLINE ... and not just lately) questions were raised
about the current state and further expansion Speccy. Many even
just wondered about the lack of resources (size and method for 
extending the RAM, CPU clock, disk size and time of access, as 
well as disadvantages TR-DOS), which repeatedly, not quite 
successfully, tried to compensate by replacing boards - iS-Dos, 
CP / M. 


   On the compatibility with the standard for Speccy talk much 
and often. I can only say here to be unnecessary and even 
harmful, because called the port # FF (to be honest, in the 
company Speccy is no port, and a glitch produced a strong 
simplification of the scheme). Most programs glitch is not 
supported, but only by the ancients, still can not be undone. 
On the dangers of this port can be judged by its 
implementation. For example, in Scorpion'e he took all 
addresses except standard, which caused some complications when 
connecting C-DOS modem.



   In the enlargement ... My thinking at the expense of Ports:
low address is created following: bits A0 - a busy port # FE and
Use of non-refundable.


    A1 - printer ports # FB and # 7B.


    A2 - base port to port # 7FFD, # BFFD, # FFFD, as well as
     used in Profi (# DFFD), Scorpion'e (# 1FFD).

A5 .. A7 - loaded, depending on the whistles: VG93 (1F, 3F,
     5F, 7F, FF), VV55 (same ports except # FF), and much more
     nothing.


    A4 - Modem C-DOS (some modem to a different address).


    A3 - the only "standard" not employed "address" (# F7).



   In the top address the situation better:


   When the low byte # FD - better not to touch! (Although # 
DFFD in 99.9% of the programs are not buggy - checked - I have 
a Pentagon with # DFFD (A15 = 1 A14 = 1 A13 = 0 on AY A13 = 1!) 
For other reasons "Standard" is not busy.



   Conclusion: To further enhance the need to use port
# XXF7, or some other reason (it is better to use the setup
programs at the base address).


   Suggest using the following scheme (Incidentally, a similar 
scheme of using the ports used in IBM): 


   Port Address: # ZYXX, where:

XX - ml.bayt base addresses of all the new ports (configurable).

Z - a part st.bayta base address, personalized for each

     device (allows you to connect up to 16 new devices).

Y - part st.bayta addresses - used to select the port

     device.


   Let me explain with an example: Suppose you have created or 
bought the damn-1, addressed to the port # 30HH, and this port 
is already hanging Hrenovina-2. You switch on the motherboard 
damn-1 pair of bridges, thus establishing the desired base 
address and the program in setup'e specify the corresponding 
base address. 


   AND NO CONFLICT OF OFFICE!


   On the poor Z-80 Say a Word ...


   Dear Sinclair Users, Lord, man, I want to ask you:
how much more you can torment hunky Z-80, forcing him to pull
excessively heavy bytes of RAM in any TsAP'y, forcing speakers 
to publish a variety of cod, noises, etc. (Do not get me wrong 
- Musicmaker'y on Speccy very good about their own well-being 
pekus). Y Z-80, and so cases lacking, and the memory is not 
rubber. 


   If you have not realized yet - I'm talking about the need to 
create devices that do not occupy the time Z-80, same DACs 
should take care of themselves (to get the vital bytes from 
memory CPU or her (which is much better). For example, if 
"normal" output sampling rate is, depending on the program, 
3000 .. 8000 bytes / sec (for single-channel music - more), 
because interrupts (which are counted musical clock, change 
tools, etc.) sound spoiled, all the while the Z-80 is busy, but 
order for output to AY often use part-time addressing that 
leads to different effects on advanced computers. When using 
the DAC, who were hanged for the devil knows what addresses the 
situation any better. And it would be good to give beautiful 
effects in games, without taking time and space to main memory, 
which are so lacking. By the way, the appearance of such a 
sound card on the market I heard something and would like to 
learn more. 


   The extension of the video. Specifically, I will not propose 
anything, although the idea is (for example the idea: separate 
RAM (64k..), Your processor, using a palette (not to be 
confused with a half-liter), and more another), offer only the 
following: 

- Use a separate RAM (will without problems increase
  Sit permission and does not slow down the CPU in turbo mode);

- Use to access this memory box addresses

  # 4000 .. # 5AFF.

            CONCLUSION


   Conclusion will be usem ... (Joke).


   I hope I have not sweated in vain, he wrote the text. People 
think invent and not too exorbitant price (C-DOS modem - 4.5

Products - 120 pieces! Red price it 20 tys.maksimum! He has 
already been long copy and to make their own). And in general, 
for spektrumistov no barriers - giving 1 GB RAM, 8 GB HDD, 200 
MHz, 14400, and so on.



   If someone hurt for anything, I beg your pardon,
as well as grammar. And voobshe, breathe deeply ...

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ON-LINE: grammar corrected ...