Optron #14 03 июля 1998

Железо

Iron - Maxi-perverted "in- bambasy "PowerZX.

                  Iron



(C) Andy Nelson, 1998


  Following the example Twinsoft and taking calls rasp, I, Andy 
Nelson (as in passport Smolsky Andrew), also decided to describe

its PowerZX, it maxi-perverted "gadgets" and then I sunk to 
this. We first give the parameters:



  Motherboard ......." Lviv option "

                    (Serves as

                    frame, as

                    spend more than

                    tracks on the board and

                    some chips

                    are three stories:))


  CPU ............... Z80H 3.5 / 7 MHz

                    71680/114688

                    cycles per frame.


  Memory field ....... common and nezatenyaemoe

                    (As in Pentagon'e)


  RAM ............... 512 kB


  ROM ............... 64 kB (firmware changes
                    Nena: after the last

                    "Sewing" out there: BASIC-48

                    TR-DOS 5.05, STS

                    5.11A, RDS 3.1, Jemmi
                    ni Commander 4.1)


  Virtual ROM ....... 64 kB (used

                    of RAM)


  Number of lines

  Vertical ...... 320


  Cycles per line .. 224 (for 3.5MGts)


  INT ..............." Pentagon "with the author
                    ically bounded
                    Niemi its length


  Graphics mode .... STANDART - 256 * 192, 1916

                    colors, attributes, 8 * 8

                    MULTICOLOR - 256 * 192

                    16 colors, attributes

                    8 * 1

                    HIRES - 512 * 192, 2

                    color

  Number of videos

  page 3 ...........


  Sound sources ... BEEPER, AY-3-8912, CO
                    VOX (9 bit)


  Drives ......... 2x5.25 "Teac FD-55 (about
                    Dean of them was

                    1.2MB)


  Joystick .......... Kempston (used

                    Standard Dendy-jo
                    ystick)


  Mouse ............. Kempston Mouse


  Printer port ..... ZX-Lprint


  Story about what it is, why it
need and how I did it, I would like to start with a little 
history of a primary alteration of my computer. Because the 
study best for each other's mistakes, I hope,

underwritten information you ever
useful.

  As I used Motherboard
charge of the "Lviv option", as in
later regretted, as this version
Spectrum, despite the great similarity with
brand has a lot of hardware defects. But since the other was 
not given, then all my experiments were conducted on this 
board. Frankly speaking, I "fuck up" two boards. First, after 
the terrible experiments still "gone" for the parts, the second 
"survived" and on that computer, I type the text. 

  First, make 48K 128K + AY was not difficult (six chip logic, 
socket by AY, actually AY, a small shawl and

about 2 meters of wire). Craving for modernization came after 
more demos "retard" or "not passed" very

(Especially Enlight'96). Also wanted more memory (up disks with 
one drive was a very "fun" activity).


  We first performed experiments on
Connection 565RU7. Computer, in principle,
earned, but on the screen to create "raving".
The fact that these RU'shki normally worked in "Scorpio" has 
pushed me to think that they "do not like the" method of 
reading information video controller. I removed "Inhibition" of 
memory, resulting in image to appear, but a problem of 
regeneration in nezatenyaemoy of RAM which, for unknown 
reasons, could not solve. In addition, the VRAM For some 
reason, there appeared a "point", and immediately after the 
four of them in any place, with a fixed distance between them. 
The intensity of their occurrence depends on the voltage 
supply. The reason for this was not possible to solve for six 
months. 

  Five months later, I got imported
analogues RU7 (i21256). They earned
"Shaded" mode to another board, but
traction to make a "netormozyaschy" computer took over. And now 
after such modifications have a problem with "points" again. 
The scheme, which, in theory, should have been working 
properly, persistently betrayed a "point" in memory. But most 
interesting was that the RU5-Tide worked fine.


  After much testing schemes "ATM-turbo",
"Pentagon128" and "Scorpion", it was concluded that the 
revamped "Lviv" option different one: as the address counter 
circuits used 561 series. Then, after gating all addresses

RU-NIS signal-CAS (through IR23)
This problem has disappeared forever. Cause
same appearance of "points" was that the vertical counters 
increment on signals obtained from the vertical sync. Due to 
inadequate performance of 561-series, in the end, it led to the 
fact that during the cycle of reading from RAM to change the 
value on the address bus. RU5-Tide is "tolerated", but RU7-mym

it "did not like."

  There was also a problem of regeneration in the nezatenyaemoy 
"area of ​​RAM. At first glance, everything seems to be there, 
but the memory still fails. Get rid of this failed, decided

problem "in the root." Was converted addressing RU-NIS: all 16 
chips now have a common address bus and common signals 
And-RAS-CAS, as an attempt to combine pairwise data outputs, 
ie, "make" operate two banks of RAM on a single register,

with separate signals-CAS, as is done in the "Pentagon'e" nor 
to no good led. Chip did not get along "between

themselves, even if the signal is fed only
-RAS. I had to put another one on IR23
output of the second bank. In general, this option has some 
advantages address: RAM properly regenerated, the signal-CAS is 
connected to the RAM directly, which increases the noise 
immunity of the computer, and even if the "burn" the memory, 
the computer can work with one Bank of RAM (256K).


  The following description is made on the basis of
the following sources: schemes
"Lviv option", "Pentagon",
"ATMturbo" or "Turbo-2 +, log
"Spectrofon 20" and the "ZX-Format 5. In addition, you should 
be patient, considerate, beer ... :) And now let's start order.




       Removal of inhibition of memory



  Schema modifications result in 'Optocouplers "
problematic for two reasons: firstly,
it is difficult to draw a text editor, and secondly, a single 
and final option scheme I do not, because

pattern during set-up adjustments, which are sometimes "forgot" 
to record. But despite this, the basic "underwater

Stones I try to describe.

  Of the three options "nezatenyaemyh" computers (Pentagon, ATM 
and Scorpion) I chose Pentagon, since it is relatively easy to

implementation and subsequent installation
Turbo mode gives the best result.

  Implemented almost entirely on the "original" scheme. In 
addition, it is necessary to replace the "half" counter 561IE10 
(D22.1) on the same counter 555'toy Series and ensure that it 
is zero at the moment the arrival of a reset signal (k.7 D22.1) 
(suitable 555IE7). It is also necessary to skip all other 
address signals through 555IR23 which should be clocked 
signal-CAS. This excludes the possibility of entering danyh of 
video RAM through KP11 (D32, D33) on the data bus of the 
processor. 

  Distribution of pages within the address
space of the processor, I did two
555KP12. On the address inputs of multiplexers
A14 and A15 are fed and given configuration
pages, the output is the address bus. This method allows
implementation of such a contraption as the Virtual
ROM. In a nutshell, the service mechanism
Memory is easily implemented on 555ID4 so
as is done in ATMturbo. When commissioning
often helps to "obveshivanie" 50-200 pF capacitor signal-RAS 
and-CAS. Must also "hang" blocking capacitors on power supply 
of RAM (preferably not less 0.15mkF on each chip).




               Turbo mode



  Some initial recommendations.

  It is best to install the processor socket (only good to you 
in Subsequently, it was not a problem). Should

also take into account the fact that in turbo mode do not work 
for all processors. Single copies like it is working, but 
"bent" connecting the periphery, as data bus and address of the 
"Lviv version" is not buffered. The best option - Z80H, mozhno 
try Z80B. Z80A and domestic counterparts do not work all. 
Sometimes do not work in turbo mode ROM-old shki

registration (before 1984).

  Turbirovanie scheme is the same as for
Pentagon'a (3 circuits), except for one:
No need to install an element of TM2
(D107.2), which excludes the possibility of
dual circulation of the processor to the memory of
reading time of one video controller
familiarity (4-cycle read). In addition,
should submit the switch "Turbo" with
controller drive signal-VG93.CS,
well-DOSEN. When working TR-DOS turbo mode
will be disconnected, but it does not matter
as in turbo mode boot faster
still no go.

  Does not work correctly in turbo mode
AUTOchecking drive many boot'ah (k
Unfortunately, it is eliminated only with the program).



               Virtual ROM



  It is a pseudo-ROM. The meaning of this 'feature' in the 
following: a bit of a special port off the main ROM, but instead

included one of the last pages of RAM
(# C5 - TR-DOS, # C6 - BASIC128, # C7 - BASIC48). Entry into a 
pseudo-ROM addresses 0 - # 3FFF not performed. Record any data 
in the pseudo-ROM would be to include a page at the following 
addresses # C000-# FFFF. Port which includes the pseudo-ROM has 
a soft "latch" (as the port # 7FFD), need relief which the 
signal-RES set switch. The result is an interesting thing: you 
can download any firmware BASIC48, BASIC128 and TR-DOS,

Engage the port configuration to translate
the computer to reset and disable 128K
port latch configuration for signal
-RES. We get a full Speccy-128
loaded firmware change that
software is already impossible. Realized this
"Gizmo" in the presence of two KP12, which specify the page 
number for each address "quarters", is relatively simple. On 
configuration inputs for the zero-KP12 quarter of address space 
served signals ROM.A14 and DOSEN. On the other input is 
selected numbers of the last pages of RAM implement port # 
EFF7, mutes, and repeatedly turning the main ROM on a certain 
signal, we realize the system RAM and a write lock in memory 
addresses 0 - # 3FFF. Assigning individual bits of the port

# EFF7 will be given below.



        Increase "frame length"



  This has, historically, that all
Spekrum-like machines contain a raster
312 lines, and Pentagon - 320 lines. Because
these eight lines, some demos, written in the Pentagon, the 
brake on your computer, which have only 312 lines (in 
particular, and Lviv option "). Solve the problem is simple: to 
"the brakes" vertical counter to eight rows. Install an 
additional count of 8 and design the system locks the vertical 
counter. Recommend the "stretch" the bottom border, if you do 
not want to have Problems with the arrival time INT'a.




           The problem of signal INT



  More precisely, two of them: the arrival time and
its length. On how to make a "firm"
and "Pentagon" INT spoken and written much (even the demo 
special was) and I will not dwell on it separately. If you want 
to know how to make a right INT for "Lviv

form ", I advise you to read to help Ram
Doctor-in Tyatina Sergei. Problem length
INT'a solved by selecting the desired rezistora or capacitor. 
But this is true only if you do not have Turbo mode. If it 
exists, an interesting problem: to pick up

length for 3.5MGts, switched on 7 - INT
became a "longish" picked up for 7MHz - at
3.5MGts keyboard works through time.
The first "threw" the idea of ​​how to deal with it, Valentine 
(Twinsoft). He suggested use the fact that the Z80 during

processing INT'a simultaneously establishes
"0" signals-IORQ and-M1. Thus,
put a trigger lock on the signal INT and
doing so he placed the signals-IORQ and-M1, and reset any
another signal, coming at a time
when INT is inactive (eg, signal BORDER). In general, the 
scheme is the following: 


   INT X to 16N. Z80

             D1.1


              1



          +5 V oR

                       Q

          GND D
-BORDER / C

        D1.2

                oS
-IORQ 1
-M1 D2.1 D1 - 555LL1

                            D2 - 555TM2


  After such alteration problems INT'om,
in Turbo Mode, disappear forever.

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