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Forum Index : Microcontroller and PC projects : New 8080A Computer
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| Volhout Guru  Joined: 05/03/2018 Location: NetherlandsPosts: 5540 |
HPNightview, Honestly, I think that (in those days) maintaining a 25000 lines source code would have been challenging anyway. And yes, now you bring it up, no call/return was a 1802 specific. Forgot about that. The PIC16 is kind of similar, it remember the return address, but you have to remember backing up you status register, since that is not part of the return. Typically you would add macro's for that in your assembler. The thing I found elegant is the bank of 16 bit registers, in stead of the limited A/X/Y in a 6502. The 68000 had similar (32bit). Volhout The radiation-hardened 1802 was still produced in 2022 (don't know 2025), so it surpassed the famous Z80 in that perspective. It is used as an IO processor in satellites. Only the 6502 is in production now from the early CPU's. Edited 2025-12-04 18:13 by Volhout PicomiteVGA PETSCII ROBOTS |
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Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 8374 |
I still like the register system of the Z80.Being able to quickly switch to an alternate register bank for a subroutine was handy. Mind you, I think we all still like the CPUs that we had experience of - well, in some way. lol A lot of fun was had looking for undocumented op-codes on the Z80. Inspection of the bits in the hex indicated that there were similarities between instructions, particularly in register pairs like HL, BC and DE, that indicated that other pairs should be possible or that some like the index register XY could be split into individual X and Y registers. All good fun. :) Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| JohnS Guru Joined: 18/11/2011 Location: United KingdomPosts: 4171 |
If writing in assembler: the PDP-11 had a great instruction set the VAX-11, too (though rather over-engineered) not so the IBM 360, ICL1900, 8080/8085, x86 and so many others. Thankfully C, even with its various issues, does rescue the situation a lot! John |
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| EDNEDN Senior Member  Joined: 18/02/2023 Location: United StatesPosts: 279 |
I like (or prefer) the Register Based architecture of the 8080/Z80 over the Zero-Page memory architecture of the 6502 or 6800. Depending upon what you have to work with you write the code different. And the BASIC interpreter of the TRS-80 and Apple-II were 'large' programs back then. They provided a lot of back and forth argument about which architecture was superior. I was impressed with how fast the 1 MHz 6502 in the Apple could execute a BASIC program. It was half the speed of the TRS-80 but its BASIC programs could compete because the Zero-Page indexing of this and that memory structure could be done very efficiently. |
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| ville56 Guru Joined: 08/06/2022 Location: AustriaPosts: 337 |
I started with Intel 4004 in 1974, handassembling test programs for some peripheral hardware, learning a lot about the supporting hardware. And a lot was required to get all the clock phases and voltages needed. Later on I used SC/MP, PDP8, 8085, PDP11 all in assembler. The VAXes I used with compilers only. My largest assembler project was a IBM 3270 emulator on a PDP11/44, over 4000 lines of code, connected to SNA via a Dec gateway over a 9600 baud line. For me, those were the days of real fun .... Looking at all the sophisticated stuff we use for hobbies nowadays, trying to keep up, I think I'm getting old... 73 de OE1HGA, Gerald |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 8374 |
erm... yeah... It's scary. I was born two years before the first working silicon transistor was made in Bell Labs. Now we can't move for the darn things. :) I used to have a manual for a 4004 (or it may have been a 4040). I think it might have been lost in a flood. :( I do know it was the first CPU data I'd ever seen and I was completely and totally confused by it. lol I'd had dreams of getting a chip (they were pretty expensive) and making it do something but that idea quickly fell to pieces. I think I might still have a V20 CPU somewhere. I don't think I have any 8088 motherboards though. Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| ville56 Guru Joined: 08/06/2022 Location: AustriaPosts: 337 |
I was born 2asc (years after silicon transistor) but I've also lost all the manuals for the 4004 and the SC/MP but i still have a 8008 CPU chip rescued from an old PDP11/34 programmers console and the MCS-8 manual. But I have no intentions to get that thing running again as I do not possess any of the support cips, even though I still have some 1K bit static ram chips and some 1702 eproms without a programmer. The work with the 4004, in course of my engineers education practice months, started my deep interest in mircros. Before I was keen to solve every logic problem with the TTL chips available by that time. And I was in the lucky situation that I got a lot of chips for free from the company I spent my practice months. Mostly on used PCBs but desoldering was not an issue. My first frequency counter was based on a 6 digit Nixie clock PCB, extended with FET frontend and autoranging, a TTL graveyard ... nowadays a few analog chips around a pico, a display of your choice, some lines of code and going up to much more than the 10Mhz possible with plain TTL. Yes, 50 years of advancement. 73 de OE1HGA, Gerald |
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Martin H. Guru Joined: 04/06/2022 Location: GermanyPosts: 1331 |
ville56, I had a similar experience. After completing my training, I bought used BTX decoder boxes cheaply on private markets (there was no eBay or internet yet). These were good TTL sources. Desoldering was quick, as the circuit boards were no longer needed. I simply heated them with a hot air gun until the solder began to shine, and then tapped them on the edge of the table. Then all the 74xx were lying on the table. Cheers, Martin 'no comment |
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