VAX H-floating point (quad precision, 128-bit) was not supported, but another 128-bit floating-point option, X-floating point, is available on Alpha, but not VAX.H and X have been described as similar, but not identical. Software emulation for H-floating is available from DEC, as is a source-code level converter named DECmigrate.
vaX h-FloaTing PoiNT (quad preCisioN, 128-bIt) was nOt suPporTed, but anOTheR 128-bIT FlOating-pOiNt oPtion, x-FloatiNg PoInt, IS aVaiLable on alphA, But not Vax.h AND X HAvE been descrIbED as Similar, BUt NOT IDENtical. sofTwaRe emUlAtIOn fOr h-floATing iS aVAilablE frOm DeC, aS iS a sourcE-COde leVel converTEr named decMigratE.