6845
The 6845 CRT controller drove the displays of a generation of home and business computers.
- Odd
- Composite
Where 6845 fits
Why 6845 is special
It generated the timing signals a cathode ray tube needed, and programming it outside its documented limits is how demoscene programmers produced effects the hardware was not designed for.
Factors & digit properties
- Divisors (6)
- 1, 5, 37, 185, 1369, 6845
- Prime factorisation
- 5 × 37^2
- Digit sum
- 23
- Digital root
- 5
Representations
- Decimal
- 6845
- Scientific notation
- 6.845 × 10^3
Roman numerals
Roman numerals as modelled here goes up to 3,999.
Binary
1 1 0 1 0 1 0 1 1 1 1 0 1
1 × 4,096 + 1 × 2,048 + 0 × 1,024 + 1 × 512 + 0 × 256 + 1 × 128 + 0 × 64 + 1 × 32 + 1 × 16 + 1 × 8 + 1 × 4 + 0 × 2 + 1 × 1 = 6,845
Octal
1 5 2 7 5
1 × 4,096 + 5 × 512 + 2 × 64 + 7 × 8 + 5 × 1 = 6,845
Hexadecimal
1 a b d
1 × 4,096 + a × 256 + b × 16 + d × 1 = 6,845
Read as powers of two: 4,096 + 2,048 + 512 + 128 + 32 + 16 + 8 + 4 + 1 = 6,845.
In historical numeral systems
Egyptian
6 lotuses, 8 coils of rope, 4 hobbles, 5 strokes
6 × 1,000 + 8 × 100 + 4 × 10 + 5 × 1 = 6,845. The signs are simply repeated and added; where they sit on the line is a matter of layout, not value.
Systems that simply cannot reach this value are left out. Where a script needs a font most readers do not have, the reading is given instead of the glyphs — see number systems for each system in full.
Other mathematical patterns
- Deficient number
Related numbers & connections
Both generate video timing, but the TMS9918 also composites sprites so the processor does not have to move objects itself.
View 9918 →Technology & computing
The 6845 was driven outside its documented parameters to produce screen modes its designers never intended. That practice — exploiting undocumented behaviour deliberately — is the origin of the demoscene.
DocumentedTechnology & computing
Common questions
Is 6845 a prime number?
No, 6845 is not prime.
What are the factors of 6845?
The factors of 6845 are 1, 5, 37, 185, 1369, 6845.
About this page's data
Mathematical facts:computed directly from the number's value — nothing to source or verify externally.
Contextual records: 1 reviewer-confirmed record, sourced and reviewed before publication.
Last reviewed: 15 July 2026