Questions tagged [zx-spectrum]
For questions about the different versions and products of the Sinclair ZX Spectrum computer
160 questions
11 votes
4 answers
1k views
Function to return free memory in Sinclair ZX Spectrum BASIC?
Sinclair BASIC doesn't have a FRE() function, which on other systems typically returns the number of memory bytes currently unused by BASIC. I'm looking for a way to find that value. The system ...
- 22.8k
13 votes
3 answers
957 views
How to remove end of snapped ZX Spectrum keyboard connector
I recently powered on my 48k ZX Spectrum (1983 Issue 3B), and the keys 1-5 were not working. I decided to open it up to see if reseating the keyboard connectors would solve the problem. Unfortunately ...
- 3,215
21 votes
2 answers
2k views
How does ZX Basic represent numbers?
I no longer have my ZX81 or Spectrum, nor their manuals, but I do remember that both floating-point and integer values are stored as 40-bit values (and the motivation for that is addressed in Why does ...
- 2,059
5 votes
1 answer
863 views
Isometric game for the ZX Spectrum, featuring a protagonist with magical powers and a decaying body, held in a castle
I played this game in the early 90s on the 48K Spectrum, on a second-hand cassette in a standard box. From my impression of the instructions and the fact it was isometric, it's likely to have been ...
12 votes
2 answers
1k views
Does the ZX Spectrum's system variable PROG always hold 23755 (5CCBh)?
At the ZX Spectrum, the system variable PROG (23635) contains the start of the BASIC program (see the manual). At my ZX Spectrum when I do PRINT PEEK(23635) + 256 * PEEK(23636) I get 23755. So a ...
- 461
5 votes
1 answer
336 views
In a 48K Spectrum why are there 5 successive contended cycles in JR?
In a 48K Spectrum, the contention pattern for the JR instruction (see e.g. https://sinclair.wiki.zxnet.co.uk/wiki/Contended_memory) is: pc:4, pc+1:3, pc+1:1, pc+1:1, pc+1:1, pc+1:1, pc+1:1 There is ...
- 496
18 votes
1 answer
2k views
Why does the ZX Spectrum ROM set I register, then wait 24 T-states?
I’m doing some low-level, interrupt-based Z80 Spectrum programming, and, investigating the ROM, found this oddity (clipped from The Complete Spectrum ROM Disassembly), in the ROM initialisation/...
- 283
10 votes
1 answer
1k views
How did one run CP/M on Spectrum computers before the Spectrum +2A/+3?
Wikipedia says, "[The Spectrum +3] was the only Spectrum model capable of running the CP/M operating system without additional hardware." (But the +2A used the same motherboard, and thus ...
- 29.5k
3 votes
0 answers
344 views
Were CP/M systems based at $4200 a "standard"?
According to the CP/M 2 manual, the standard locations for BOOT (where you jump to do a warm start) and TBASE (the start of the transient program area or TPA) are $0000 and $0100, respectively. This ...
- 29.5k
12 votes
1 answer
990 views
Are there official, standard, or conventional names for the screen RAM addresses on the ZX Spectrum?
I'm working on a disassembly tool for the Sinclair ZX Spectrum and want to do things "right" when possible. I remember seeing lists of ROM routines, system variables, and memory addresses ...
- 8,214
2 votes
0 answers
289 views
Lower RAM module design for ZX Spectrum [closed]
While the upper DRAM chips for the ZX Spectrum (4164) are more stable and still accessable, the lower DRAM chips (4116) will become a critical component in the future. One of the solutions to this ...
- 121
3 votes
2 answers
493 views
Can anyone tell me more about flippy games?
I remember having a number of Mastertronic tape games for the Amstrad CPC 464 that could be used on a Spectrum too by using the other side of the tape. These were called flippys I believe. Was this ...
- 131
9 votes
1 answer
748 views
How many commercial Spectrum ROM cartridges were released?
According to this site, Sinclair released a total of ten titles on cartridge: all games that were popular on cassette, and all in 1983, the year the Interface 2 was released. I know the cartridges ...
8 votes
0 answers
306 views
What were the licensing terms for The Hobbit? [closed]
The Hobbit was a 1982 illustrated text adventure game released initially on the Spectrum, based on the Tolkien novel of the same name. According to https://www.filfre.net/2012/11/the-hobbit/ Unlike ...
- 65.4k
7 votes
5 answers
3k views
Spectrum DIY upgrade to 48K
The ZX Spectrum was initially sold in 16 and 48K versions. Every owner of the former version who continued using it, inevitably ended up wanting the upgrade to the latter. (I get the impression it ...
- 65.4k