HDscheme, option #2

I’m willing to bet that no one has succeeded in repeating the scheme option #1. :) A considerable
part of the blame for this lies with me...

During testing of the subject, two unpleasant features of the
Pentagon-128 boards were noticed. First: writing data to DD62(TM9, port register #7FFD)
is not done as expected. As a result,
if the processor is slow or there is a reactive load of a significant
size on the data bus, data will be written to this port with glitches. It can be cured by inverting the sampling signal of this TM9.
Second feature: the /DOSEN signal, before getting to the 1st ROM pin, is mixed with A14 and A15. The benefit of this is a debatable issue, but the result is brakes with Basic/TRDOS ROM switching. Here you need to
from DD76:9 go directly to DD36:1, cut off the old signal from DD36:1.

In the diagram (below) this is all reflected.

Tested on two Pentagons and one Leningrad clone.

........................................................................

(c)1998-1999 AXLR
════════════════════════════════ ════════════════════════════
Modification of the controller to work with HD disks, option #2
══════════════════════════════ ══════════════════════════════

Here is a turbo mode diagram that provides moreHigh
performance than the old one. The new one according to tests gives
more than 113000 cycles/int.
There is also an improved circuit for switching
the VG93 clock frequency, now this should work on any
Pentagon.

──────────────────────────────── ───────────────────────────
Scheme of turbo mode Z80-7MHz for the Pentagon-128 computer
──────────────────────────────── ───────────────────────────

*100pF
D1.1 ─┬─ D2.1
┌──┐ === ┌──┬──┐
DD3:2 ────1│ &o3──┴─────13o R│ │
DD3:3 ────2│ │ ┌────12│ D│ _│
└──┘ │
DD15:5 ──────────────┘ │ └──┴──┘
+5V
^^^^^^ We take all signals from the computer board.

D3
┌──┬──┐
DD45:3 ────────2│A0│ │
+5V ───5│A1│ │
├──┤Y0│4─────>DD45:12
DD2:9 ────┬───3│B0│ │
┌─────6│B1│Y1│7─────>Z80:24
│ │ ├──┤ │
+5V D2.2 ┌──────1│ S│ │
│ ┌──┬──┐ ││ │┌15oOE│ │
├─1o R│ │ ││ │─┴─ └──┴──┘
__ ┌──2│ D│ _│ ││ │
M1 (Z80:27) ─────────3/ C│ Qo6┘│ │
│└─4o S│ │ │ │
│ └──┴──┘ │ └───────────────┐
│ └───────────────┐ │
D4.1 └──────────────────────────┐ │ │
┌──┐ │ │ │
/bit7#FF───1│ 1│3────┐ │ │ │
DD76:9 ────2│ │ │ │ │ │
└──┘ │ │ │ │
+5В D5.1 │ D4.2 "NORMAL" │ │ │
│ ┌──┬──┐ │ ┌──┐ S1 │ │ │
HLD──┬──1o R│ _│ └─ 4│ 1│6 ───── \ │ │ │
│├─2│ D│ Qo6────┬─ 5│ │ ┌─ \──────┘ │ │
/IP─────3/ C│ │ │ └──┘ │ │ │
│└─4o S│ │ │ D6.1 │"TURBO" │ │
│ └──┴──┘ │ ┌──┐ │ │ │
│ └─ 1│ &│3 ───┘ │ │
└───────────────── 2│ │ │ │
└──┘ │ │
/IORQ ─┬──────────────┐ │ │
│ D7 │ │ │
│ ┌──┬──┐ │ D4.3 D6.2 │ │
└14│ R│ 0│ │ ┌──┐ ┌──┐ │ │
+5В ──11oWR│ 1│ └─10│ 1│8───────4│ &│6──┘ │
┌─5/+1│ 2│6────── 9│ │ ┌─5│ │ │
│ ├──┤ 3│ └──┘ │ └──┘ │
│ │ │ │ │ │
│ └──┴──┘ │ │
└─────────────────────────────────────────┘
│
D6.3 D5.2 │
┌──┐ ┌──┬──┐ │
Z80:26 ──10│ &│8─────13o R│ _│ │
DD49:11── 9│ │┌─────12│ D│ Qo8──────┘
└──┘│ ┌───11/ C│ │
Z80:28 ────────┘ │ ┌10o S│ │
DD50:13──────────┘ │ └──┴──┘
+5B

Сигнал HLD берется ВГ93:28, /IP - с ВГ93:35,
/IORQ - с Z80:20, а /bit7#FF - см. ниже.

─────────────────────────────────────────────────────────────
еобходимые переключения/доработки на плате компьютера:
─────────────────────────────────────────────────────────────

1. Отсоединяем DD5:2(ЛИ3) от Z80:28.
2. Отсоединяем DD15:1(ТМ2) от +5В, подаем на этот DD15:1
сигнал /RFSH (Z80:28).
3. Отсоединяем Z80:6 от DD1:8(Л 1) так, чтобы осталась связь
между Z80:6 и резистором, соединяющим его(резистор)
с +5В.
4. Сигнал с DD45:10(ТМ8) подаем на Z80:6.

5. заменяем цепь VD2+R13 в схеме контроллера на элемент
ЛИ1,we find the free electronic element LI1 on the computer board:

as it should be:

C39 ───┐
│ LI1 DD76(TM2)
DD77(LL1) LI1 │ ┌──┐ ┌──┬──┐
┌──┐ ┌──┐ └─│ &│────13│ │ │
│ 1│11 ───┬───────│ &│────│ │ │ │ │
│ │ === C3 ┌─│ │ └──┘ │ │ │
└──┘ ─┴─ │ └──┘ └──┴──┘
│
DD78(AG3) │
┌─────┐ │
│ │12─┘
│ │
└─────┘

6. The signal coming from DD64:13(LE1) is disconnected from DD62:9(TM9)
we pass it through the existing electronic circuit LA3 and only then
we feed it again to DD62:9, like this:

D2.3
┌──┐
┌─10│ &o8───> DD62:9
DD64:13 ──┴─ 9│ │
└──┘

7. Signal from DD76:9(TM2) apply to DD36:1 (27c512), disconnect the old
signal from DD36:1;

8. If necessary, replace DD76(TM2) with a faster
series 1533.

──────────────────────────

Actually, a modification for switching the clock frequency of
VG93 + modification of the “turbo-VG”.

Two circuits are given here, the first takes into account the presence of sections in the
controller that use a frequency of 8 MHz (for example,
a PLL circuit); the second is for controllers; there are no such sections
having.
Without modifications, the Pentagon controller uses
only 4 MHz, so if the PLL is not
detected in the controller circuit, it makes sense to install a second
on such Pentagons diagram.

────────────────────────────
If there is a PLL on the 556RT4, then we assemble the following:
───────────────────────── ────────────────────── ───────────────

D10.1
┌──┬──┐ D6.4 +5V
VG93:33─1о R│ _│ ┌──┐ │
┌─2│ D│ Qo6──13│ &│11┬────────────┐
VG93:38─3/ C│ │ ┌─12│ │ │ │ D8.2 │
/STEP───4о S│ │ │ └──┘ │ │ ┌──┬──┐ │
│ └──┴──┘ │ │ └1o R│ Q│5────────┐
─┴─ D8.2 └┐ │ ┌2│ D│ │ │ │
┌──┬──┐ │ │┌─3/ C│ _│ │ │ D1.2
┌─13o R│ │9──┐ └──4o S│ Qo6┐│ D9.1 │ ┌──┐
D7─────12│ D│ _│ ││ ││ └──┴──┘ ││ ┌──┐ └4│ &o6─ DD76:3
DD88:9─11/ C│ Qo8─┤│ │└─────────┘└1│ 1│3─5│ │
├─10o S│ │ ││ DD86:6─┴────────────2│ │ └──┘
│ └──┴──┘ ││ 50..150 Ohm └──┘
+5V │└──███─> "HD/DD", feed to the "HD/DD" microphone
│ in the drive (see. below).
│
└──> /bit7#FF

Signal D7 - taken from Z80:13.
/STEP - from the disk drive connector.

In the controller, the old signal coming from DD86:6 (L 1)on
DD76:3(TM2) - cut off. Instead of 8 MHz, we supply
a signal from D1:6 to the PLL circuit (LA3 is being finalized, see above).
Instead of 8 MHz quartz we put 16 MHz quartz. If the DD86 (L 1) series
155 or 555, it is recommended to replace it with 1533L 1. Otherwise
the generator assembled on this DD86 may not start.

─────────────────────────
If there is no PLL on the 556RT4, then we collect like this:
────────────────────────────

D10.1
┌──┬──┐ D6.4
VG93:33─1о R│ _│ ┌──┐
┌─2│ D│ Qo6──13│ &│11─┬──> DD76:4
VG93:38─3/ C│ │ ┌─12│ │ │
/STEP───4о S│ │ │ └──┘ │ D9.1 D1.2
│ └──┴──┘ │ │ ┌──┐ ┌──┐
─┴─ D8.2 └┐ └─1│ 1│3───4│ &o6──> DD92:3,
┌──┬──┐ │ DD86:6 ──2│ │ ┌─5│ │ DD92:11,
┌─13o R│ │9──┐ └──┘ │ └──┘ DD93:2
D7─────12│ D│ _│ ││ DD76:5 ──┘
DD88:9─11/ C│ Qo8─┤│
├─10o S│ │ ││
│ └──┴──┘ ││ 50..150 Ohm
+5V │└──███─> "HD/DD", we feed it to the "HD/DD" microphone
│ in the disk drive (see below).
│
└──> /bit7#FF

We take the D7 signal from Z80:13.
/STEP - from the disk drive connector.

In the controller, disconnect DD76:4(TM2) from +5V;
cut off the signal coming from DD76:6from DD92:3(TM2), DD92:11
and DD93:2(IE10) so that these three pins of the microcircuits
(DD92:3, DD92:11 and DD93:2) are connected between yourself.

────────────────────────────

Microcircuits used in the modification:

D1: 1533LA3, D2: 1533TM2, D3: 1533KP11, D4: 1533LL1,
D5: 1533TM2, D6: 1533LI1, D7: 1533IE7, D8: 1533TM2,
D9: 1533LL1, D10: 1533TM2.

Any microcircuit, except D1(LA3), D8(TM2) and D9(LL1) can
be replaced with a similar one of the 555 series. If quartz-16 MHz
was not used, all microcircuits can be installed in the 555 series.

As you can see, modifications have already been assembled here "turbo-VG". If
it was already installed on the computer being modified, then you do not need to install
exactly the same el.t TM2, but you need to take an existing
signal (inverse trigger output) and apply it to
D6:13 of the modification.

The “HD/DD” signal is recommended to be supplied to the disk drive
microphone through the 2nd reserve contact (numbered as 4th on
disk drive connector) - for 5.25" (1.2M) drives this is
a standard disk rotation speed control signal
(300/360 rpm). And for 3.5" (1.44M) drives this is usually
a free contact.
The HD/DD mic is located on the motor board, above
the "HD" hole in the drive (it is usually sealed). and on one
leg of the mikrik there is usually a common wire, and on the otherthe control signal for the drive chip is removed
. Here we send the “HD/DD” signal to the second
leg of the mikrik.

Attention! If you connect a 5.25" (1.2Mb) disk drive, then
you just need to send the "HD/DD" signal to it, and
you don't need to modify anything in it, everything is already there.

* * *

When installing this modification not on the Pentagon, the main
problem is coordinating the control of the turbo mode
modification with the turbo circuit in the computer. Everything else
is done the same as on Pentagon: a modification is being made to the
controller to switch 8/16 MHz frequencies, adding
bit7 to the system port of the controller (port #FF) and assembling
a “turbo VG”, if it does not exist yet, you need to pay attention
to the presence of a /wait driver in the turbo circuit when accessing
the processor to the ports. If such a section is missing,
it is recommended to assemble it, for example, as suggested above
. (here collected on IE7 and LL1).

If the computer has software control
of the turbo mode, the "turbo/norm" switch can be done
as shown below:

D4.1
┌──┐
/bit7#FF───1│ 1│3────┐
/DOSROM ───2│ │ │
└──┘ │
+5V D5.1 │ D4.2 LA3 LA3
│ ┌──┬──┐ │ ┌──┐┌──┐ ┌──┐ TURBO'
HLD──┬──1o R│ _│ └─ 4│ 1│6 ─────│ &o─────│ &o────────>
│├─2│ D│ Qo6────┬─ 5│ │ ┌───│ │ ┌│ │
/IP─────3/ C│ │ │ └──┘ │ └──┘ │└──┘
│└─4o S│ │ │ D6.1 │ ЛА3 │
│ └──┴──┘ │ ┌──┐ │ ┌──┐ │
│ └─ 1│ &│3 ─────│ &o────┘
└───────────────── 2│ │ │ ┌─│ │
└──┘ │ │ └──┘
ЛА3 │ │
┌──┐ │ │
┌──│ &o─┘ │
├──│ │ │
│ └──┘ │
TURBO ─────┴─────────┘

где: /DOSROM - сигнал в контроллере, низким уровнем
переключающий (страницы) ПЗУ с Basic на TRDOS;
TURBO - сигнал программного управления турбо-режимом,
высоким уровнем включающий режим "турбо" Z80.
/bit7#FF - см. выше;
/IP - ВГ93:35;
HLD - ВГ93:28.

..............................................................

До свидания, All.