henning@thor.acc.stolaf.edu (Mark D. Henning) (03/29/89)
good day, I am thinking about embarking on a fun project (i hope), being that I want to build a memory board for my amiga 1000. I do nees some advice, however. 1. what function do the 3 autoconfigure lines have. How do I tell the OS how much new memory is added, or does it do a memory test on reboot. 2. I have figured out that I need to use 16 chips because of the 16 data port lines. Aside from memory chips and buffer chips, are there any other components I will need to consider. 3. If I were to think about adding a self-contained uart thus making a serial port, how would I let the configure know about it. (Im sure that I will ahve to make a custom driver for it, that, i'm not worried about.) 4. If anyone has an idea how to make the battery backed up clock taht the 501 board uses, I would also like that option. I want to do this for several reasons. First and foremost is the fun of finally being able to make something hardware related for a machine (i prevoiusly had a c128 which made hardware addons very limited!) Also, the prices of prefab memory boards are outrageous! Any help or insites would be appriciated. Thanks in advance. -henning Internet: henning@stolaf.edu uucp: ..uunet!solaf.edu!henning
cmcmanis%pepper@Sun.COM (Chuck McManis) (03/30/89)
In article <1686@thor.acc.stolaf.edu> (Mark D. Henning) writes: > 1. what function do the 3 autoconfigure lines have. How do I tell the >OS how much new memory is added, or does it do a memory test on >reboot. Get the hardware manual for the A1000. ($20 from CATS, 1200 Wilson Dr, West Chester, PA, 19380) It explains the bus, autoconfig, and how to build the expansion hardware. [It assumes you know digital logic already] >2. I have figured out that I need to use 16 chips because of the 16 >data port lines. Aside from memory chips and buffer chips, are there >any other components I will need to consider. This is not a good sign Mark. DRAM memory design (assuming you are using DRAMs) requires some refresh logic, the memory chips, some address line drivers, and a passing knowledge of transmission line design. You should probably read the Texas Instrument's DRAM design application notes (part of their Memory Book (a catalog of DRAM chips)) or the Intel DRAM design notes which is part of their databook on RAM chips. >3. If I were to think about adding a self-contained uart thus making a >serial port, how would I let the configure know about it. (Im sure >that I will ahve to make a custom driver for it, that, i'm not worried >about.) Using the knowledge gained from the autoconfig discussion in the A1000 schematics stuff, you can deduce how to make an autoconfigured serial port. >4. If anyone has an idea how to make the battery backed up clock taht >the 501 board uses, I would also like that option. If you get the A500/A2000 technical reference manual from CATS ($40) you can look at the A501 schematic. Or use the design from the A2000. >I want to do this for several reasons. First and foremost is the fun >of finally being able to make something hardware related for a machine >(i prevoiusly had a c128 which made hardware addons very limited!) Building new hardware for your computer is always interesting and fun. The risks are that you can fry your computer, which is not fun. When learning hardware design, one should always strive to become an excellent diagnostician first, because as in programming, most of your time will be spent tracking down bugs. Before you start, be sure you have access to schematics to your machine, a logic probe, a PAL programmer, and at least a 100Mhz dual trace oscilloscope. A logic analyzer is nice but not essential. Then as you progress, incorporate your new knowledge into later designs. In fact you may wish to design the UART circuit first, this would entail learning how autoconfig works and setting up a board to use it. Then this same knowledge can be applied to the memory design. >Also, the prices of prefab memory boards are outrageous! Outrageous is a relative term, given your questions I believe it will take somewhere between two to nine months for you to complete your homebrew memory board. [It depends on if you can work full time or if you have to restrict your work to evenings and weekends]. Plus you may end up repairing your Amiga one or more times. The cost of the parts you will require will be in the range of $250 to $450 depending on the size of memory board you make. Plus you will probably want to build a PC board although a wire-wrap board will work for a while. Do you have the stuff to make a PC board ? [UV lamp, etching tray, photo enlarger, etc] How about the stuff you need for wire-wrap? PC's will set you back about $100 for a good setup, and about $50 a board. The wire-wrap stuff is cheaper, more like $50 setup but the wire-wrap sockets are more expensive. This is not meant to discourage you, only to point out that the difference between you building it and you buying it may be a couple of hundred dollars _at most_. When you consider that, the prefab prices are not nearly so outrageous. In fact they can look like a bargain nine months from now! >Any help or insites would be appriciated. Thanks in advance. > -henning Free insites available here. I'm one of those weird people that got there degree in Electrical Engineering but make their living programming. I've designed and built boards professionally, but find I like the ability to create test equipment out of thin air (eg program it) rather than go through purchasing to get it. --Chuck McManis uucp: {anywhere}!sun!cmcmanis BIX: cmcmanis ARPAnet: cmcmanis@sun.com These opinions are my own and no one elses, but you knew that didn't you. "A most excellent barbarian ... Genghis Kahn!"