╔════════════════════════ ═══════════════════ ═══════════════════╗ ║ Beta Disk Interface. ║ ╙─────────────────────────────── ───────────────────────────────╜ (C) EVP-SOFT Hello everyone. Today I will talk about several improvements controller and disk drives. All these improvements have been tested in practice. ke, and the first of them is on my BBS. I don’t specifically write num- walkie-talkie outputs of microcircuits, because the microcircuits used here have several identical elements, and find them in the circuit diagram of your computer, the circuit shown in Fig. 1 would be very difficult. 1. Turn off the engines of inactive drives. If you have two or more drives, then when accessing one All of them rotate. This creates many problems, such as noise, overheating of the power supply (especially during formatting). This happens because the engine is turned on by a signal START, and a specific drive is selected using signals SELO...SELЗ. However, the circuit design of all the controllers that I seen (Profi, GRM, Scorpion, Atas, Pentagon), does not allow issuing send SEL signals in the absence of a START signal, SEL signals and START are always present simultaneously. Thus, observing There is some redundancy of signals. To eliminatethis problem, each of the drives needs to Replace the START signal with the corresponding SEL signal. For this you need on the drive board, cut the track that comes from 16 pins connector stroke, although you can completely remove the corresponding wire (START) from the loop. After which, the track on the drive board, which paradise previously went to pin 16 of the connector - now it needs to be connected to a jumper on the drive that determines its number (0...3). The START signal can now not be taken beyond the control limits at all. Lera. Now, when the SEL signal is applied, the engine will only turn on the drive on which the jumper is installed, the corresponding giving the desired SEL signal. 2.Installing drives C and D. On some computers (for example, Scorpion, Atas, some Pentagons) the circuit design of the controllers does not allow installing drives C and D. This is connected ┌──┬───┬──┐ ┌──┬───┐ with the fact that on these controllers - │ │TM8│Q0├─────┤ D│LP8│ pax an incomplete decoding was made - D0──┤D0│ │ │ ├──┤ Q ├─SELO disk drive number (is- │ │ │QOo─┐ ┌─o E│ │ only 1 bit is used in total - ~~~~~~~~~~~ │ │ └──┴───┘ then 2), and therefore when reversed - ├──┤ │ │ │ │ to drive C or D pro-VHS─┤ C│ │ │ │ │ ┌──┬───┐ access to A or B RES─o R│ │ │ └───┤ D│LP8│ respectively. Usually, there └──┴───┴──┘ │ ├──┤ Q ├─SEL1 used something like this START─────────────┴─o E│ │ scheme as in Fig. 1 where for Fig. 1 └──┴───┘ using only the D0 bit, connection is possible only two drives, because when choosing, for example, drive D in the register records the number 3, and this is D1=1 and D0=1. Well, as follows - from the diagram in Fig. 1, bit D1 is unused, thus obtaining The number is 1, and this is drive B. To connect drives C and D, you need to do a complete decryption radio drive number, i.e. use bit D1. for this you You will only need two microcircuits - 5SSTM9 and 531ID14. Instead of mik- If you use a TM9 circuit, you can use a TM8 chip. In general, it is necessary to select drives by ┌──┬───┬──┐ ┌──┬────┬──┐ scheme shown on D0──┤D0│TM9│Q0├───┤V1│ID14│Q0├─SELO Fig.2. So, first you need D1──┤D1│ │Q1├───┤V2│ │Q1├─SEL1 cut tracks that ~~~~~~~~~~~ │ │ │Q2├─SEL2 come from the outputs of LP8 (Fig. 1, ├──┤ │ │ ┌─o E│ │Q3├─SELЗ SELO and SEL1), the inputs of these VHS─┤ C│ │ │ │ └──┴────┴──┘ two LP8 elements too RES─o R│ │ │ │ can be disconnected - they are └──┴───┴──┘ │ will no longer be used - START───────────┘ Fig.2 to be. Then all the pins of the TM9 chip (Fig. 2) are bent, except 1,8,9,16, (i.e. R,0V,C,5V) with which it is soldered onto similar conclusions of the TM8 microcircuit (Fig. 1). Then they are fed to TM9 signals D0 and D1, they can be taken directly from the Z80. Then put ID14 and the new circuit is ready. All that remains is to bring it to the loop but- high signals SELO...SELЗ. 3.SelectionFM/MFM. In the original Beta Disk Interface diagram, bit D6 of the FF register controls the recording mode, FM or MFM. However, on controllers, which have incomplete decoding of the drive number, this bit (i.e. D6) is usually not used and the controller can work Only available in MFM mode. Although I don't know of systems that use re- press FM (TRDOS, MSDOS, ISDOS - this is all MFM), you can do this possibility, especially since if you assembled the circuit in Fig. 2, then you just need to set bit D6 to one of the free inputs of TM9, and connect the corresponding TM9 output to pin 37 of the microcontroller lera VG93, but first pin 37 must be disconnected from the circuit. However, the computer improvements do not end there, and soon, maybe I'll tell you about how GRM's ZX-Lprint 3 upgrade to a standard LPT port. This will allow full handle printer errors (of course, not 6312, but with a higher class she), and also connect ZX and IBM, then in IS-DOS, if available appropriate driver, you can quickly transfer files to MS-DOS/NC and vice versa.
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