[2/2] BETA-DISK-TURBO-HD

(Continued.)

and here, in fact, is the scheme for finalizing the controller
BETA-DISK-TURBO into BETA-DISK-TURBO-HD :)

BQ1: 16 MHz DD9
┌──┬──┐
┌──────┤█├───────┐ DD86:6───2│A0│ │
│ DD8.1 DD8.2 │ DD8.3 DD93:14──5│A1│Y0│4───> on DD76:3
│ ┌──┐ ┌──┐ │ ┌──┐ ├──┤ │
├1│ 1°2─┬─3│ 1°4─┼─5│ 1°6──────────3│B0│Y1│7───> instead of 2MHz
│ └──┘ │ └──┘ │ └──┘ DD93:13──6│B1│ │ under revision
│ K43 │ K43 │ ├──┤ │ TURBO-VG
└──███──┴───███──┘ ┌─────1│ S│ │
│ ┌─15°OE│ │
DD5.2 │ ─┴─ └──┴──┘
+5V ┌──┬──┐ │
├─13° R│ Q│9──────┴──── to the HD/DD microphone in the drive
D7(Z80:13)───12│ D│ │ (see below)
D88:9 ───────11/ C│/Q°8── /bit7#FF
└─10° S│ │
└──┴──┘
Microcircuits:
DD1: 1533KP11, DD2: 1533LE1, DD3: 1533TM2, DD4: 1533LL1,
DD5: 1533TM2, DD6: 1533LI1, DD7: 1533IE7, DD8: 1533L 1,
DD9: 1533KP11
Any microcircuit except DD8(L 1) and DD9 (KP11) can be
replaced with a similar one of the 555 series, this will only be reflected
in the load on the power supply.
Old signals going to DD76:3, 2 MHz on TURBO-VG - CUT OFF!

Signal from DD5:9 modifications going to the HD/DD microphoneThere is no need to buffer in
the drive (I have never buffered it,
and the cable to the drive is 1m, and everything is OK). The HD/DD microphone itself is located on the motor board, just above the “HD” hole in the disk (it is usually sealed). and usually a common wire goes to one leg of the microphone, and the control signal
for the microcircuit is removed from the other. Here we send the "HD/DD" signal to the second leg.
Yes,
from the disks now you HAVE to remove the stickers (3.5" stickers are insanity..). If you are going to use 720K 3.5" disks (they don't have "HD" holes), pass the "HD/DD" signal
through a 50..100 Ohm resistor in advance, and only then apply it to Mikrik
in drive.

Actually, in the Pentagon this 16 MHz generator would not be
needed, but because... Almost all Pentagonists have a PLL at
556PT4, then the circuit is given taking into account its presence in the controller.
If there is no PLL, then DD76:6 must be supplied to DD9:2, DD9:3 -
DD86:6, and then you need to cut off DD76:6 from DD92:3. If there are still 2 LE1 elements left free, you can not install L 1, but
try to assemble a 16 MHz generator on them.

How does it all work together?

The density mode (normal/high) is switched
by software, bit7 of the #FF controller port: bit7=0 - normal,
bit7=1 - high density. Fortunately, it so happened that all
programs that work with the diskThis bit is always kept in the same state: zero. Having made the modification, you can safely
run the old programs, they will work just as before
with 360K-800K disks.
I must say, without a turbo it doesn’t work, because... the exchange rate increases exactly twice (2 MHz is supplied to VG93 instead of 1 MHz) - now it is more than 60K/sec. By turning on the turbo mode when executing a program from DOS ROM, we ensure that the Z80 still has about 112 clock cycles per exchange cycle, and it, the Z80, works with the VG93 in the same way as at the usual density.
and the high density fits up to 18 512-byte sectors on the disk (format 1.44M) or up to 10 1024-byte
(non-standard, but also format - 1.6M). Thus,
MSDOS (PS/2) HD disks are easily read/written.
After the turbo has been modified, it will always turn on during
disk operations, but only after the disk has had time
to spin up. If the exchange with the disk is at normal density, the turbo mode can be turned off using the "TURBO/NORMAL" toggle switch (interestingly, this was needed for one and only
program: FUT by MI&DI). If the turbo was turned on, it
is turned off while the disk is spinning up, and then
turns on again.
When positioning for revision, TURBO-VG always goes
2 MHz, unfortunately, at a higher frequency the VGshka does not work.

According to rumors, at somefrom the two reserve contacts of the connector
of the 5.25" drive there should be a signal to control the speed
of rotation of the engine. But on my Mitsumi, both reserve ones don't
go anywhere. So, I sent the "HD/DD" signal through the 2nd reserve
contact (numbered as 4th on the disk drive connector) - and it works fine for me, and on the PC.

P.S. All designations of the elements are given according to that diagram Pentagon, in which the Z80 address signals are designated A1-A16. Unfortunately, there is no way to do without removing the drive casing, but all
alterations in it are one wiring.
==============

All the best.
Roman.