======== Newsgroups: comp.sys.cbm Subject: COMP.SYS.CBM: General FAQ, v3.1 Part 7/9 From: brain@mail.msen.com (Jim Brain) Date: 13 Aug 1996 01:01:37 -0400 X-Posted-By: YPost, version 0.08 Archive-name: cbm-main-faq.3.1.p7 Comp-answers-archive-name: commodore/main-faq/part7 News-answers-archive-name: commodore/main-faq/part7 Comp-sys-cbm-archive-name: main-faq/part7 Version: 3.1 Last-modified: 1996/08/12 --------------------------------------------------------------------------- Table of Contents (for this file) --------------------------------- 10. Emulators 10.1. What is an emulator? 10.2. What platforms do 64 emulators exist on? 10.3. What platforms do 128 emulators exist on? 10.4. Are any other Commodore computers emulated? 11. Troubleshooting 11.1. What do I doisk drive? 11.2. What do I do for my ill computer? 11.2.1. What do I do for my ill Commodore 64? 11.2.2. What do I do for my ill Commodore 128? 11.3. What do I do for my ill keyboard? 12. Modifications and Cabling How can you alter which side a 1571 reads from? 12.2. How do I open a C128 power supply? 12.3. How do I make a cable to hook my CBM 1902A to my 64 or 128? 12.4. How do I build a simple RS-232 interface cable? 12.5. How do I build a 2400/9600 bps RS-232 interface cable? 12.6. How can I determine how much VDC video memory is in my C128? 12.7. How do I build a GEOCable interface? + 12.8. How do I connect my Commodore printer to an IBM PC? --------------------------------------------------------------------------- 10. Emulators As time moves on, people move to other computer systems, for business resons or otherwise. However, many still long to play Commodore games, use Commodore software, and enjoy Commodore demos. Thus, emulators were born to bring the non-Commodore computer owner the enjoyment of owning a Commodore. 10.1. What is an emulator? An emulator is a piece of software that runs on a given platform and emulates, or mimics, the operation of another machine. When the emulator loads up a program, the programs runs as though it were running on the emulated platform. | For more information on emulators and their use, please see The Commodore | emulator FAQ, maintained by Ken Gifford (tsrken@voicenet.com). I can also be found on Jim Brain's MAILSERV serve 6.5.2 for more | information). For those with WWW browsers, the CBM Emulation FAQ is at: | http://www.hut.fi/~msmakela/cbm/faq/ 10.2. What platforms do 64 emulators exist on? 64 emulators exist on the following machines: Amiga IBM Atari ST Macintosh UNIX 10.3. What platforms do 128 emulators exist on? There is a very basic Commodore 128 emulator bundled available for the UNIX platform under X. It is bundled with X64. 10.4. Are any other Commodore computers emulated? There is a commodore product called the PET emulator that remaps a Commodore 64 to emulate a PET 40 column unit (i.e. PET 4032). You can run this program on a C64 to emulate a PET, or you can run this program | on a 64 emulator to emulate a PET on an IBM, for example. + As for VIC-20 emulators, one exists for the Amiga, and there is a program + similar to the PET Emulator that allows a C64 to emulate a VIC-20. For the + UNIX OS, one called VICE is available for machines with X Windows. Contact + Andre Fachat (a.fachat@physik.tu-chemnitz.de) for more information. The + emulator is at: http://www.tu-chemnitz.d Although not necessarily a different Commodore computer, there is a GEOS emulator in the works. It is called GEOS Warp v1.0 and information is available at http://stud1.tuwien.ac.at/~e9426444/geoswarp/index.html. A version for the Apple PowerMac is in the alpha stage, and support for a PC version. Plans for a UNIX/X11 version are still unclear. The author is Andreas Varga, and can be contacted at e9426444@stud1.tuwien.ac.at. 11. Troubleshooting 11.1. What do I do for my ill disk drive? If the drive spins and the LEDs are off: At the back of the 1541 circuit board are two bridge rectifiers - stout epoxy packages with 4 leads each. The innermost one is defective If both LEDs are dim: The 5VDC regulator is bad. If both LEDS are on: Drive did not make it through the power-on reset sequence. Kernal ROM (901229-05) is susepct, as is (in order of expectation): VIA (6522), CPU (6502r equivalent), or a "glue" chip in the reset logic If your drive won't even accept input from the computerght is making some blinking pattern, then the drive may be telling you what is wrong. No Blink Kernal (E000-FFFF) ROM or 6522 VIA Failure One Blink 6116 RAM Failure Two Blinks Possible Zero Page RAM Failure Three Blinks DOS (C000-CFFF) ROM Failure Four Blinks DOS (C000-CFFF) ROM Failure Five Blinks 6116 RAM Failure Six Blinks 6116 RAM Failure | Six Blinks 2114 RAM Failure at c4 or c5 (8050) Seven Blinks 6116 RAM Failure Eight Blinks 6116 RAM Failure 1541 The most common problem facing the 1541 disk drive is alignment. If your 1541 has trouble reading commercial disks, or reading disks written some time ago, but has less trouble reading recently written disks, chances are that your 1541 is out of alignment. C= service centers will typically align a 1541 for anywhere from $20 to $45. There are also 1541 alignment programs, (e.g. Free Spirit's "1541/71 Alignment System") which allow you to align a 1541 yourself. There are those who claim that this does not produce good results, but there are others who claim to have had satisfactory results with these programs. There were a couple of articles in COMPUTE Gazette and I think RUN on how to do this. The real problem is mechanical in nature and can be over come. Other products are PHYSICAL EXAM 1541 and 1571 versions. 1571 The C=1571 drive is normally a double sided drive. However, it can also emulate a 1541 and read single sided disks. Some of the earlier 1571's had oldes (ROMs) which caused a couple of problems. One, these older drives were typically very slow when writing to the back side of a disk. Two, it would take these drives ~30 seconds to go into single sided mode. To chead the error channel of the disk drive right after startup. On the 128, just PRINT DS$. On the 64, use: 10 open15,8,15:input#15,a,a$,b,c:close15:printa,a$,b,c | Run the program; if the message says v3.1, you have the newer ROM. | If it has a version 3.0 or older, you have the older ROM. One problem that might occur is not having the head close enough to the disk as required because of the light tension of the spring that pulls the head down. Somewhere I remember that there was supposed to be a replacement part. However, one of the alignment programs suggesting using pennies to weight it down and lo and behold it started working. 1581 The C=1581 drive is a 3.5" drive that uses DSDD 800K disks. It is compatible with both the C64 and C128, although some programs will not work correctly with the 1581. A small number of 1581's were shipped with an early version of a controller chip which has problems with some software. 11.2. What do I do for my ill computer? At times, every computer must be serviced. As the parts supply of Commodore equipment dwindles, servicing becomes harder. However, there are many sources in Section 16.2 that can service your Commodore machine, and here are some things you can do to service it yourself. If the screen is garbled, but BASIC seems to be limping along, and any command is met by an error, RAM could be bad. You can look at bit patterns on the screen by determining screen codes for garbage characters. only bit 4 (32) should be on. After you determine which bits, here is the bit->IC mapping: Bit 7 (128) : U12 Bit 6 (64) : U24 Bit 5 (32) : U11 Bit 4 (16) : U23 Bit 3 (8) : U10 Bit 2 (4) : U22 Bit 1 (2) : U9 Bit 0 (1) : U21 A common problem with the C-64 is it's power supply. The C64 power supplies are not especially powerful, and have this disturbing tendency to fail. If your computer stops working, first check the power supply. Replacement power supplies can be obtained from a number of mail order places (e.g. Tenex, Parsec, Inc.). Additionally, several places advertise "heavy-duty" power supplies that come with warranties, and give the C64 enough power to run a REU. If your power supply goes, it can sometimes take other parts of the computer with it. If your power supply has died, but the C64 continues to fail with a known working power supply, it is likely that a few of your chips got fried. Also, another common problem with the C64 is the fuse inside the computer. If the system power on light comes on, but you get a blank screen, suspect the fuse. It is usually blown by misinsertion of devices into the computer. 11.2.2. What do I do for my ill Commodore 128? Like the 1571, the C-128 has an older ROM and a newer ROM. The differences between the two are less serious than is the case with a 1571. The easiest way to tell the difference is to click down the CAPS LOCK key and hit Q while in BASIC direct mode. If you see a lower case q, then you have an older ROM. If you see an upper case Q, then you have a newer ROM. ed from (e.g. Paxtron Corporation) for about $25. The ROM | chips in the 128 are all socketed, so replacing the chips is relatively | easy. 11.3. What do I do for my ill keyboard? Clean it: Materials you will need: Denatured (rubbing) ...
Amiga7878